As a hiring manager, I've never cargo culted this particular view. In fact I think it's completely misguided. I always work in at-will states, it's trivially easy to let someone go. I also personally have no problem doing it.

I generally will hire based on conversation alone (no coding tests). If you ask someone detailed questions about work a candidate has done you can get a really good idea if they know what they're talking about. I know people say that they've interviewed people that can talk a good game but can't code a for loop once in the door, but I've interviewed hundreds of people and I can't say this is often the case.

Easy in, easy out. You know what though? There's very rarely ever the out part. If I can look at your Github, like what I see and you can back that up in a conversation, you're hired. That has worked out really well for me and reduces a lot of friction and wasted time (mine and other engineers') during the hiring process.

The moral of my story is that just because Google or some other tech giant espouses a theory like "false positives are way more costly than false negatives", it doesn't mean it works for all organizations or that it's even true at all.