> I've only done take homes for companies that I've already passed initial interviews for and generally like the people I've talked to and have favorable impressions of the culture/workplace thus far

So your experience has been quite specific. A lot of companies think that it's fine to send you a take-home assignment as the first step. Some more do it after just a 10 minute phone call.

I'm not saying you're wrong, just that your amazement can easily be explained by the fact that you've done it in particular circumstances which is probably not the experience of most people.