How does the smart card collect dollars from any given banker bot?

The assumption is that the holder of the smart card is an adiabatic better in a dollar trade for bot coins. So the smart card has all the information about making a dollar bid. Once you decide how many bot coins you will spend for a dollar, its done, right there in the smart card, ready to spend. Your choice to sell bot coins for dollars is committed once you sign in with the pass code on a purchase.  The merchant and the buyer decide when to clear the account. If the account is cleared immediately, the merchant has to send your bid to the appropriate banker bot, with account clearing informations.

Any better on a dollar/botcoin exchange is simply holding the second derivative of price in  the personal account.  The account holder is assumed to be within range. The issue of credit ratings still remain. The account holder increases its store of the second derivative by making bets that move the bot closer to maximum likelihood. If the whole group just bets against the bot, then no dollars or bot coins exchange and everyone, including the bot, lines up on spectral boundaries. The system is useless, it is not measuring an external. The entire basis of a buyers club is to  provide signals so buyers can move purchases into sequences that insure less volatile goods flow and they costs lower. They borrow the second derivative from each other.

What about digital cash withdrawal?

An ATM machine. Put in your smart card. The ATM will direct the connection to your banker bots, no matter how many, your smart card can bid with them all.  You rithdraw $200 in digits, the smart card makes the deals, you have $200 digits at the no arbitrage price, comprises of withdrawals and or deposits, with many banker bots,  in units of your second derivative. Your second derivative is your online wealth, it is a measure of your ability to move prices slight off from maximum likelihood.  But the key here is that all your favorite banker bots trade with each other.

Your card can handle multiple currencies, you can load up on Walmart points, early, if you think you are doing 'out of band' WalMart shopping.  Out of Band means you are a bit adiabatic from your transaction band, doing a bit of splurge shopping.  Going on a trip? Pile on the flyer points, hotel discount points.  You, the customer add information to the bots when you use their trading skills, they become better at it.