OP is not incapable of doing the job though. I also worked the front counter and drive thru at a fast food chain. I got a couple mean comments from customers, but who hasn’t? My coworkers never complained about my stutter and neither did my boss. I could do everything fast except talk. When I was on the cash register I would speak very politely and calmly, which is good customer service anyway. Also, how can we expect people to accept us if they never interact with us?