1. The trouble with your solution is that there would be too many, especially Lookie-Lous, taking perishable time that cannot be recovered.
Seems you don't travel much. Airlines. You board, you don't like the cabin crew, you get off - good luck getting a refund. Hotels - refund only if cancellation is made 24 hours prior... Same with tours, cancelling because you don't like the tour guide's attitude... Even car rentals - sure, a LARGE corporation can "average out", but a small business... they wouldn't be in business long. And if they really had too many customers cancelling because of poor performance "cars", they'd be out of business.
Bottom line is, you're not paying her for sex, you're paying her for her time. And if you walk with your "solution", there's a good chance she cannot recover that lost money for that time. It's why airlines OVERBOOK.
2. If you don't like their methodology, then simply patronize
businesses where you can walk-in, view a line-up, and pay after.
https://youtu.be/1Ar5OdHtQrA?t=65