Really, the only people I see likely getting caught out on this are tourists leaving with unused balances. The argument that "they get the money sooner" seems like nonsense to me. They get the money when you put it on the card, either way.

Re: the tourists, Metro in DC has an approach that I assume is for charging tourists more, which is that paper farecards (instead of the reusable SmarTrip card) get a surcharge of $1 on each trip. They're very open about the surcharge, so if you don't like it, then you can get a SmarTrip; however, it would then take a pretty involved computation to end up with zero balance at the end.

I'm actually pretty favorable toward the DC policy. Increasing tourist revenue (who probably are going to be pretty willing to pay slightly more for limited subway use) in a tourist-heavy spot seems like a reasonable approach to subsidizing the heavier commuting users of the system. With Metro specifically that may not be a huge deal because so many people have their commuting paid for as a benefit, but I like the basic idea.