Three things comes to my mind when I see these type of discussions. Volatility, Fee structure, and the speed of tx.
Volatility is something not new to crypto users, we accept crypto thinking that eventually, the price will go up. The problem with this thought is that you need to have back up funds if the market gets into a correction and you have to buy more stock to run your business.
The Fee has to be put on the buyer, so unless it is less than 1-2% of the total transaction, most of the buyers will back out on paying through crypto.
The speed of the transaction is also an important factor as the tx has to be confirmed instantly or at least under a minute otherwise it will be harder for stores that have a crowd of customers.
I have seen stores accepting crypto, most of them prefer TRX, XRP, or LTC.
Also, we as a community have to start using crypto in transactions and not just hold them forever..