I worked in the service industry for many years and I think it's safe to say you are just one in an endless stream of faces.
4everalone wrote:I always look them in their eyes and say "hi", but often I see their dislike for me, and is met by silence.
You're probably misinterpreting/projecting, avoidant-style. Cashiers have boring, monotonous jobs, and it's easy to let your mind wander as you work. Perhaps they were just thinking of something unpleasant in their lives and not actively disliking you.
I would say with a large degree of certainty that quiet, AvPD people are by no means met with disdain by cashiers or bus drivers or waiters or anyone who deals with the public. On the contrary; these are the types of people who made my job just a little more pleasant. It's the complainers who I dreaded to deal with. Or the people who wanted to make small talk.

They were the worst, not the quiet, shy or otherwise unassuming people with whom I was able to carry out my transaction with with a minimum of fuss. Trust me, they probably APPRECIATE you!
And if for some reason you encounter an a-hole cashier or bus driver (If I had
that job, I'd probably scowl at
everyone) who does dislike you for some unfounded reason, I'll bet you are totally forgotten by the time the next person comes along and "annoys" them.