Employees really have to do their homework before joining and do their own interviewing as they’re being interviewed, carefully observe the organization during their visit, read Glasdoor reviews, talk to former employees, etc. You won’t get everything, but you‘ll be surprised how much you can find out before joining if you ask gentle but pointed questions.
You’re right in that it’s challenging for companies to implement this philosophy. It takes real guts on the part of the board and leadership team to truly practice a “no asshole rule”. My hypothesis is that these companies will naturally outperform in the long-term by attracting and retaining the best talent.