Do you know why? Because these shops have massive difficulty to bank/accept card payments. They were pushed out of fiat system because they sell something that's legal but the banks are against.
Discussion
It isn’t the banks that are against it, they’ve been very much involved in the drug trade. It’s because of the laws and regulation they’re subject to.
One way or another, the vendors know what being financially excluded means. That's why they #Bitcoin. Wait until you lose your financial privileges.