Note that a restriction on commercial sales still does not make an item itself "illegal".

I'm not trying to ignore the existing of the activation energy of having to spec/get/install your own showerhead rather than automatically having a default you like. But it's clear that amount of market friction here is much less than say, the outright digital authoritarianism currently going on with phone apps. And it's important to keep this perspective, lest memes about "illegal showerheads" morph into groupthink that supports different authoritarian movements.