I haven't had to do a warranty return (for auto parts) via Amazon. Generally, I don't get anything with a 'lifetime' warranty through them.
With RA, while I've not had to return anything yet for warranty purposes, I do know that when I look up items from previous orders, that if anything on that order was 'eligible', a button appears next to that item to initiate a return. The benefit there, being that I don't have to worry about receipts, registering the item, etc. So that's a plus, I guess.
I know that I would *not* like having to pay for return shipping of the new part / old one; if that's what I have to look forward to (per
@Mooseman), I may reconsider my purchase strategies to lean more toward retail (most of the time, the retail stores are easily double the price - but if I'm paying shipping both ways, especially on heavier parts (lower control arm assemblies, anyone?), I could see that delta narrowing between RA and retail, in a hurry.
I know that my local parts stores (AAP, AZ) also keep a record on their 'lifetime' parts they sell me, and I don't have to register them or save receipts. About the only 'lifetime' thing I have on this basis from the local stores is the alternator in my Envoy (bought 'new' AC Delco, not 'reman', etc. I remember the store recorded the S/N on the item) Maybe a couple of Moog parts; not sure.
Since the Moog parts aren't serialized, maybe that's why
@Sparky was able to return them to his local store - ? (figuring that they do so much volume with Moog that it'll 'all wash out', anyway)
I do like 'local' - but I'll admit that since most of my parts purchases are not 'need it today' items, that I don't purchase local as often as I'd like. Other times, I can only get the part via shipping; at that point, we're just talking price, since that's my only option from all sources.
One thing I *do* buy 'local' on are batteries -- at Wally World -- because they're everywhere in the country. Like Sears used to be. Only more so. So if I'm out camping, etc. - it's the easiest way to get a new battery via warranty, should I ever need one. Most are open 24hr, too.