In Colorado, the dispensaries take cash only, most have an ATM inside or nearby. The state has been trying to set up credit unions or similar bank like operations in order to simplify the banking issues for the dispensaries (both medical and recreational) but it's been problematic based on federal law and the uncertainty of which way the legal winds may blow. By necessity there are games played with business entities to handle the cash and the bills (taxes, rent, utilities, etc).
Some place in Colorado don't allow recreational sales, only medical sales- Colorado Springs being the most notable example. Pot sold to medical card holders is taxed at a much lower rate than recreational sales. Medical only stores are very strict in that only those persons who have a medical card are allowed into the shop. All pot stores in Colorado have two parts- the front room where your id is checked (over 21 or a medical card depending on the store) then you are allowed into the room where the pot is kept and you can make your purchase.
Our sheriff does have a warning for those applying for a CCW that a medical pot card is a statutory prohibitor for firearms ownership and for a CCW. For your CCW the state does run a background check, but I don't know if they cross reference the medical card database.
The electronic 4473 my LGS uses does state that pot use is federally illegal despite what state law says. In addition to the federal brady check, Colorado does a state records check on firearm purchases, but again I don't know if they cross check the medical card database.
