Tell me, in 1400 year, moneylender thought about 0% comission of credit? They are gived credit with 4,5% yearly rate. And they dont knew, why credit with 0% comission maybe profitable... But my bank upper my overdraft level without percent in card. Magic? And maybe I make tools which make dice with 0% HE profitable 
There's no magic in that, if they don't charge any fee in your credit card then they certainly are profiting on other things. Casinos could change one of their games house edge to 0% if they're very desperate for players, volume, etc. but if they want their casino to last longer they need to at least have games with an house edge or profit somewhere else( like selling ad slots on their site or charging withdraw fees).I think if dice have a specially coin for betting, it maybe profitable without HE