Just today I claimed warranty for a mechanical part from Changan after the warranty was already expired so I don't think it's fair to assume the worst without actually trying that first.
If they don't honor warranties (which the Big 3 try to weasel out of all the time), their reputation would completely tank while exposing them to legal liability. Warranty terms are legally binding and the terms and conditions cover things in detail.
I've claimed warranty for a lot of things (electronics, appliances, gadgets, mechanical stuff) in the past without too much hassle right here in Pakistan so our experiences might be different, but we shouldn't presume malice here without any evidence.
BTW, you can also completely flip this argument around and say Japanese cars don't offer long warranty periods because their failure rate is a lot less, i.e. they don't need it because it doesn't make sense to offer a 10 year warranty on a Camry right? Everyone knows its a workhorse and will run for generations. So, a manufacturer offering 10 year warranty is reason enough that things will fail quicker and their extended warranty is a hedge. Japanese cars last longer than Korean and Chinese cars while offering shorter warranty than both globally.
I'm sorry but this argument didn't make sense to me.
A warranty is a manufacturer putting their money on the line saying if their thing breaks, they'll fix it without cost. It has a financial cost and legal risk associated with it that a company needs to justify to shareholders. If I'm Toyota and I'm sure my Camry won't break for 10 years, then I have absolutely no risk offering a 10-year warranty on it. Toyota's advantage isn't that it won't break, it's that when it does break, it would be very cheap to fix it.
Also, look into why Toyota is having so many issues lately (including in Japan with multiple models breaking) and you'll figure out why they don't offer long warranties anymore.