wrote:

I don't like their union much, but all the controllers I've talked to
have been real nice and helpful, even when I was in the middle of a
mistake.

Same here.

I've also met some in person during tours and noted that many of them
are also pilots, some are CFI's and CFII's. So in the long run, many of
them fly in the same system they work on.

They're still people.

Nothing that involves human intervention is infallible, but humans
cross-checking other humans can drive the chance of an error becoming
more serious higher than Powerball odds.