Sorry about your bad experiences interviewing. The interview does need to be a two way conversation because the company needs to know the candidate and the candidate needs to get to know the company. If they treat you like crap during the interview, they’ll probably treat you like crap when you work there.
I’ve found that a person’s raw technical ability is not as important as their ability to work in a team, empathize with the customer, have enthusiasm for the project, and generally get along with other people.
Blame the lawyers for the lack of reason for rejections. Providing a reason for a rejection just opens the doors to all manner of unpleasantness, usually involving more lawyers.