Back in the old days, almost no Sonic had a public bathroom and if they did it was pretty nasty. And the pay and reimbursement for Sonic shops was minimal. Then about 10 years ago, the reimbursements and fees went up. And Sonic apparently decided it wanted all its Sonics to have bathrooms. For a while, the previous MSC wanted a photo of the bathroom. Then the pandemic happened and the bathrooms were all locked. No bath photo requirement with the current MSC. Some have a public bath and some don't. A lot of the ones that had a public bath before the pandemic have stopped offering it, taken the restroom signs down and locked the doors. A friend who works for Sonic told me they have had problems with homeless individuals or criminals entering the bathrooms doing drugs, making a massive mess, or waiting there and mugging customers. Since most are outside toward the back of the building, it is easy for someone to walk in without being seen. When I arrive at Sonic, I drive around the building. If there is a door marked bathroom, I check it. If not, I report public restroom not available. I have done a bunch of the shops and haven't had a single question and my shops are always accepted. I figure if there is no sign customers can see, then there is no public restroom available to customers.