You can't get around regulatory requirements. You either meet them, or you don't get to sell your cars in the US. There is no negotiations, no exceptions, no allowances for anything.
And it is a federal requirement that they warranty the emissions control devices for 100K miles, not the engines, not the transmissions, the emissions control devices.
So if you were the CEO of a major auto manufacturer, what would you do? You'd probably meet all the requirements so you could sell cars, and then make darn sure the emission control devices lasted at the cost of literally everything else. Because that's how you make money, and at the end of the day, you're in business NOT to make cars, you're in business to make money.
If the government wasn't getting in the way, the car manufactures would make cars that lasted longer because reputation flat sells cars. How many people out there buy Toyota's for no other reason than reputation, and they pay a premium for those low option vehicles too.
So don't blame the greedy car companies, blame the idiots that have literally no clue what they're talking about that make the regulations.
...