As developers we have a number of failsafes and checks and balances in our processes: code reviews, TDD, unit through to integration testing, audit trails on every byte of code changed etc. To suggest that a wrong hire is "too costly" is ridiculous.
Compare this with a management consultant who is often on client site alone and whose work is heavily based on personality - "the airport test" - any wrong move could end up risking the client relationship with the business.
The "too costly" mantra really is ridiculous, exactly. Maybe we also need to make sure the people trusted with hiring other people learn that their job is not risk assessment or risk management, but finding great talent.
As for me, I've been around long enough to remember sleeping under my desk during a 72 hour shift at a Web 1.0 dot-com I worked at when I was 19. I can't imagine many others with 10+ years industry experience subjecting themselves to multi-day hiring gauntlets. If I'm right, they must be excluding a lot of experienced people. But then again, startups are so focused on speed and output at any cost that maybe excluding us mid-career types is part of the design.
But having an intensive hiring processes doesn't guard you from hiring the wrong person. So they fail again and again, while making the hiring process even harder every time. Its a death spiral. You can easily spot a startup stuck in this death spiral if someone trusted with hiring other people tells you they get a lot of applications but none of them are any good.
I'm sorry that doesn't help you much in your situation, but I hope it explains why you see a lot of defunct hiring processes these days.