\]this 1959 ticket for TPiR[/url] states contestants are chosen from the audience. I don't think I knew that.
Quizmaster went into that a little, for daytime game shows back then I don't imagine there was a lot in the audition process other than do you know the rules, can you play the game capably (TPIR was fairly simple as games go) so rather than having lots of testing to see if someone can get close to the price of a Thunderbird pick three people, get them acclimated and away you go.
I believe I heard on a $20,000 Pyramid show that Dick said some contestants were drawn from the audience as well. I think with stakes and difficulty the audition process became more intricate