Because the middle part is easy. Its the ends that are impossible.
You have to pay suppliers and you have to pay employees/overhead.
I am sure, that in only a little while, all of those people will accept cryptos,
however, right now the stores need a way to convert a lot of cryptos to cash.
They could probably do some bang-up business with a bitcoin-ATM
RE: How a Blockchain Startup Is Going to Free the Cannabis Industry from Banker Control