Does Amazon have an incentive to offer FDE, or is it just a support burden for them?

I ask, without much cynicism. How many of their customers will care? Will this lead to a PR problem for them? My guesses are few, and probably not.

Meanwhile, if someone forgets their password and can’t get their stuff, that could generate a lot of annoyance.

EDIT: To be clear: I value FDE personally, and use it wherever I can.

I'm sure it is a support burden, but perhaps no more than it is for Apple or Google in iOS and Android.