At my company when we bring you onsite for an interview takes you to lunch. The person who takes you to lunch is not allowed to talk to the people making the hiring decisions. You can thus talk about whatever you want. It is a relaxing situation where you can safely press about what work is like. If you talk about something that in an interview is illegal (likely family) it doesn't matter because that person doesn't have a say on if you are hired.
(I encourage anyone who does interviewing to have a similar policy - if someone flys in to talk to you that means you are buying them meals anyway. Ensuring there is time to talk about things that might or might not matter is important)
For engineers we wouldn't go to a fancy restaurant. However I'd expect executives probably would.
Why would interviewees believe you? I have heard such claims before and assumed they were false and treated lunch as just continuing the interview while doing something we all had to do anyway. If the interviewee raised numerous red flags, the interviewer would absolutely be sworn to silence? Even informally?
I wouldn't blame them for not. However our integraty means we will anyway. And that the lunch people don't have a voice is carefullp monitored by hr just in case something goes to court.
(I encourage anyone who does interviewing to have a similar policy - if someone flys in to talk to you that means you are buying them meals anyway. Ensuring there is time to talk about things that might or might not matter is important)
For engineers we wouldn't go to a fancy restaurant. However I'd expect executives probably would.