My schedule changes too often to do a deposit. I've never had to cancel on a provider within a couple hours of the appointment. I try to be respectful enough to avoid booking if I don't think I will be where I can meet. That said, I did have two providers verify meeting times, last week, and cancel within an hour of the meeting. Kinda goes both ways, sometimes.
Just to add my experience to the the discussion - twice over the past several years ( in moments of weakness ) I have made a minimal upfront deposit of $ 50.
BOTH WERE SCAMS !
Ms. K - I don't know the solution - but I would advise NEVER make an upfront deposit !