Credit Card to eCash

What would be the problems in setting up a web site to make a charge to a Credit Card/ATM card number and return Cash, like an ATM for the net? I belive this would be a easy tool to promoat wider use of eCash. Not everyone wants to go through setting up an account at Mark Twain or whereever, just the advantages of a more cash like system. With a few sites like this around, and hopefully therefore more eCash in the wallets of the public this could help to add to a critical mass to eCash and so on. I don't think it would create the critical mass nessary for eCash's success, but at least another log on the fire. anyway... myers