I use an
ECV full time. Each WDW resort I stayed at had space allowance for mobility equipment. I also visited other food courts at resorts I wasn't staying at, and they were fine, too.
The only problem I have at the food courts, and it's not much of a problem, is reaching the beverage machines. They are set back on the counter, and it's a little stretch to reach from your seat. Happy to say, you are guaranteed to find a helpful guest or CM to assist you in just a few moments, with no sense of helplessness. It's actually a great way to start a conversation with other guests who are loving their visit just as much as you are.
For exiting/entering the food court from outdoors, if you aren't at an automatic door, a guest will come along to open the door for you in moments. So you don't have to worry about driving your ECV, juggling food/drink, and operating a door all at the same time. WDW is very accommodating for visitors in ECVs and wheelchairs.