The supervisor/manager doesn’t want someone who knows more working under them. Puts their position into question. It’s better for them to hire someone who makes them look vital.

You aren’t alone. “But where could they be? I don’t see… Ooh!”

Difference in what: chance of pregnancy, std protection, orgasm rate/intensity, clean-up, intimacy/trust… There’s a lot of variables at play and answers will vary based on every woman and her life experiences.

Thank you for saving the rest of us from obsessively puzzling this out.