Because they do not sell it, they do not equip it on their forces, and the few times they interact with it, it's either considered junk or used in desperate plans because of its nature as materia rather than its nature as a summon. And there is no evidence that any of the summons in their posession were deliberately created by them for that purpose (where as most other types are sold in stores and thus can be inferred to be manufactured deliberately). Pretty simple.
....I have
no idea what evidence or explanation you're looking for that would satisfy you.
Yes, they do not sell summon materia in FFVII.
Shinra also doesn't sell mastered magic materia, or even materia at half-level growth that contain "ara" or "aga" level spells. Yet their SOLDIERs and high level infantry use some it.
They certainly don't sell Enemy Skill materia. Yet you find one just lying in the open in the Science Division.
Cait Sith, who comes from Shinra, is equipped with Manipulate materia. A materia that you cannot purchase anywhere.
Shinra doesn't sell Shinra Beta or Alphas, either. They don't sell Ziedrich armlets, or Tough Rings. Yet they're equipped by their troops and the Turks.
Something not being on sale doesn't make it different. That only makes it
scarce. Scarce for the general populace and individuals not privy to Shinra's resources meant for their company members. The Ultimania Omega literally says Shinra has been making materia for years, and has a monopoly on the materia business. They're not necessarily selling all available types of materia, because they're keeping the most potent kinds for themselves due to its rarity and power. And not everyone can presumably use a Summon materia because they can't control it.
Yet FFVII shows Shinra in possession of at least 3 separate summon materia. The Hades materia, on board the Glenika which carried troops, monsters and weapons to be deployed to fight Sephiroth. The Odin materia in Hojo's safe inside the Shinra Manor. And Ifrit materia, on board the Shinra Cargo Ship where troops were on board before being brutally killed by Jenova. That's not even factoring in the Huge Materia themselves or the summon materia that's created in places like Fort Condor.
So in all those instances where summon materia is literally shown in the possession of individuals connected to the company or found where their soldiers congregate, that's all just coincidence to you? Just because no grunt or SOLDIER is shown to be able to actually summon with it, doesn't mean Shinra can't make summon materia for their elite SOLDIERs and assets capable of utilizing it.
If one were to acknowledge the Compilation itself, you'd see that is exactly the case. But even casting the Compilation aside, there's no evidence at all that says Shinra can't make it, or understand it. It being rare and unusable by the majority of the populace is more an issue than anything else.
So? By your logic all materia can be artificially processed by the Shinra. What's it matter if it's Holy or Meteor? Mind you, I do not believe it possible for them to do so, but I'm taking your logic and running with it, since the statement does not state anywhere "We can create all materia...but not that special knowledge of the Ancients!". My point is not all materia are equal, and summon materia seems a cut above the likes of magic or command or support materia, based off of their nature as summons (which in FF lore generally are considered fairly special, in which nothing in the OG contradicts that).
Again, nothing in the OG says
anything about summons being special, a cut above or unfathomable to Shinra. They're simply shown to be rare. Not everyone can use them. And some summons are stronger than others. But that does not make summon materia simply impossible for Shinra to create. And it doesn't make summon materia equivalent to Huge Materia. And trying to insert outside Final Fantasy logic before acknowledging what is shown in the Compilation is pretty funny given the irrelevancy of one, and the tangible continuity of the
other.
The Black and White Materia come from the planet itself from the time of the Cetra. They were created from the lifestream not just a mako reactor. The age, density and origin of the materia make it far above anything artificially created. Shinra can't create a materia using the whole planet.
So no, Shinra can't create
all materia. I never said they could. Unique and powerful materia takes
many years,
lot's of spirit energy, and then a certain spirit energy to create materia on the level of say, the Black Materia. Huge Materia are shown to be created by Mako Reactors sucking the energy rich mako from locations abundant with life. But Shinra can't just make any materia they want because it would involve controlling the spirit energy of the planet.
Aerith can't hear the planet anymore in Midgar? What? She hears it plenty in Midgar. The Condor reactor's surroundings are also degraded. Most locations around reactors are degraded, which is sorta the thematic point of the reactors in the first place. The Midgar reactors are never stated to have Huge Materia at any point in the game. They aren't even considered in the discussion (by either Shinra or Avalanche) about Huge Materia. There is something about the Midgar reactors specifically that prevents them and I do not believe its the location.
No she doesn't by her own admission. While in the Shinra Building and talking to Cloud.
Aeris
All I know is...
The Cetra were born from the Planet, speak with the Planet, and unlock the Planet.
And...... then...
The Cetra will return to the Promised Land. A land that promises supreme happiness.
Cloud
...Speak with the Planet?
Aeris
It's full of people and noisy. That's why I can't make out what they are saying.
Cloud
You hear it now?
Aeris
I, I only heard it at the Church in the Slums.
In Midgar, Aerith can only hear the Planet... In the church.
And what's in the Church? The only spot in Midgar where plants, vegetation,
life, grows.
Aerith does not hear the planet anywhere else in Midgar by her own admission.
Aeris
Mother said that Midgar was no longer safe. That is... my real mother.
'Someday I'll get out of Midgar... Speak with the Planet and find my Promised Land.'
...That's what mom said.
Ifalna couldn't speak to the planet in Midgar either. Not sure how much more evidence is needed to show that Midgar is uniquely depleted of life and spirit energy, to the point that the only vegetation that's alive in the entire wasteland, is in Aerith's church. The planet can only be heard there because the spirit energy is
that weak.
It still provides insight into the thought process behind their placement in the setting. They were clearly conceived of as a separate category not just for gameplay purposes but also for the world building.
It was deleted. The only insight one can obtain, is that it was conceived at one point in development, and then chosen to be removed from the final draft of the game. The world building that exists in the final game is what I'm focusing on, and muddying that scope with concepts that have been discarded makes the point even more convoluted.
....They already don't wanna use what's actually shown in the setting of the Compilation, why in the world would I wanna to then use concepts that have been tossed out?