There's typically far more monetary value in product in any weed shop than there is cash, likely by an order of magnitude. Many of the purchases are done electronically, so there's not as much cash as you might think in most dispensaries.

How are these purchases done electronically if the stores cannot process credit cards? After there dispensaries more commonly using crypto that I don't know about?

they charge debit, so it's basically an atm withdrawal at point of sale.

Up to the 1990s (and probably still to this day, IDK how electronic payments have impacted this) there was a whole industry dedicated to getting cash off business premises and into banks.

For example, banks often had special "night safes" allowing small business owners to drop off bags of cash outside of branch opening hours. Some businesses would get daily armoured car visits to collect the day's takings. There were even supermarkets with a system of pneumatic tubes allowing cashiers to transfer money to the back room without leaving their stations, so their tills never had enough cash to be worth robbing. You could also get safes with a deposit slot, so employees could drop the takings into the safe, but didn't have the combination needed to get anything out again.

Assuming these all still exist, there are options for keeping cash secure, and getting it off the premises fast.

Of course, by similar logic they could store all the product in a safe out of hours. Jewellery stores manage to store loads of diamonds without getting robbed, after all...