> Why is this behavior legal for manufacturers but maybe not for Amazon? I can see no other reason than the law is path-dependent and arbitrary.
Market share => market power => different regulations.
(Of course, I would personally prefer to ban this behavior across the board; I just wanted to also point out that treating Amazon differently could plausibly be reasonable)
Those arrows also flow in reverse just as well. Whatever arbitrary decisions are made will advantage some other entity which may or may not currently exist.
Different regulations => market power => market share.
Market share => market power => different regulations.
(Of course, I would personally prefer to ban this behavior across the board; I just wanted to also point out that treating Amazon differently could plausibly be reasonable)