This is NOT true "Toyota doesn't make brake pads or rotors. They provide a specification to a supplier, and the supplier then either makes them themselves, or gets them from yet another supplier. Whether that's higher quality than what that supplier sells themselves is hard to say."
Toyota makes their own parts and their specification and tolarance is 100%. They make their rotors, and pads are made by Sumitomo. No part maker in the world can make a part to match or exceed the quality of a part made by toyota.
All my toy's still have factory alternators (new brushkit installed), factory starters (with new contacts), factory AC compressors (no freon leaks!) all wheel bearings (except hilux and 4R rears). So much to list. All are above 220K miles. find anyother car maker that has this same quality and consistancy.
Just for clarity, you believe that Toyota, an automotive OEM, owns a foundry where they melt their own materials to cast into rotors for their entire range of vehicles. Then somewhere else, they own a different factory where they build all the various pieces that go into an alternator. And for washer fluid pumps. And pistons. And a farm with cows for their own Toyota leather.
Toyota, just like every other vehicle manufacturer in the world, does not make the vast majority of their parts. They have higher standards on their suppliers than many other OEMs but they use the same tier 1 suppliers as every other car company. Delphi, Centric, Akebono, and many others, are called tier 1 suppliers or integrators, and they generally supply systems, such as infotainment or braking/ABS. After that, you get tier 2 folks, that supply specific pieces of systems, such as calipers, bearings, screens, and switches.
It makes absolutely zero sense for a top level manufacturer to try and be a generalist - a company that specializes specifically in certain things is more efficient and more profitable. Today's supply chain issues wouldn't be nearly so bad if all the parts were manufactured in house - but they're not, and when you can't get parts from location A to location B to build something, welcome to 2021.
I'm amazed by how many people out there believe that their OEM makes the best stuff in the world and no one else can touch them. Feel free to visit any BMW forum to see your words parroted back, but talking about BMWs instead of Toyotas.