But if Moen, for example, has a lifetime warranty for a lot less
money...? I went to HD looking for a replacement part for a Moen faucet
in my in-laws' house. They said, "Just bring in the old part and we'll
replace it." They didn't care whether the faucet came from HD originally
or not.

Per

Good point , But it's like the auto parts with a lifetime warranty, After
you put in the third starter you figure it out and go to the dealer and buy
one. Turn off the water, pull the fixture, go to store, explain the problem
( that's were the hoping starts) Get the part, drive home, install the
fixture, oh crap this not same anymore.