If I'm interviewing at multiple companies and they all do that, that's 4 hours per company I want to check out. And let's be honest, most of these I've been asked to do weren't reasonable to do, and do well, and double check, in four hours, despite the claim. Eight hours is more reasonable to do them properly, usually.

If I interview at three places, that's three days of unpaid work (or 6+ evenings after I've already worked a full day at my normal job), and if I'm already making "multiples of the median American family's income" elsewhere, then it becomes less attractive to put up with that, especially if other companies aren't asking for it.

Like I just can't find the energy to put up with Amazon's 2.5 hour span of unbroken time take-home test, no matter how desperate they make themselves sound or how often they contact me (which is almost every week at this point). When I last considered it, I was already having trouble juggling just finding holes in the day to manage about 30 interviews I ended up doing, across about 8 companies. I had no energy to study for, and then do, that exam on top of it (I did do three 45-60 minute exams, across three evenings, for three other companies, though).