Where I lived, decades ago one store tried this. They ended up folding because no one wanted to deal with inserting coins, why:
1. What if you had no coins ? Most people in the US dump all coins in a big jar when the get home. I would guess back then, about 30% of the people never carried coins, so the chain instantly lost some market share. Now it is more like 90%.
2. These days, just about everyone under 35 do not carry cash, never mind coins. Back then, this was not too much an issue.
3. At the time, homeless people would cruse the parking log, breaking the device to get the coin. The store would have to replace the devices often.
FWIW, where I buy food, I would sat only 10% or less carriages have issues. Years ago it was much higher but I guess the chain does something different that other chains.