YC's standard deal (at least according to their FAQ) is for 7% equity. So I think it is quite likely that YC startups do hold the majority interest.
As for other scenarios, I can't really speak to that - I personally have never been with a company that accepted any deal that included loss of control. I'm sure it happens, it just doesn't match my experience.
As for other scenarios, I can't really speak to that - I personally have never been with a company that accepted any deal that included loss of control. I'm sure it happens, it just doesn't match my experience.