The solution to the first problem is making sure the scooters are only wide enough to fit a normal sized ass. Perhaps have a manager or trained cashiers there to unlock the scooters for the customers, and if it's a fatty, say something like "My apologies, but our scooters aren't designed for people with your disability" Thankfully there's no law saying the store has to accommodate 'disabilities' like fatness with plus sized electric scooters, and stores just have them as a courtesy. Even the large sized scooters aren't wide enough for a lot of these fatasses.