3.91% is better than a slot machine (5-10%) and the play is a lot slower. Unless I’m missing something it would be a better way to spend and evening at the casino*. Improving on it, even a little bit, without memorizing perfect play tables would be easy.
*In almost all cases, spending an evening at the casino is at odds with potential income/losses.
Is that literally just on exactly 20 (so they can still stand on 17, 18, and 19), or is that “hit on anything that’s less than 21”? Because if the latter, it’s not a game any more; it’s just a way to give away money.
Actually, it’s probably that even in the “exactly 20” case, too.
I went through 20+ variations that are being played in the US and didn’t see anything. Maybe a poker derivative that allows the deal to change hand between friends? My best guess.