There must be a reason they’re not allowed in the Mos Eisely cantina. Maybe Wuher is just a dick?
Could be that they take up space that could be used by someone who actually will buy something.
“We don’t serve their kind here” is a pretty blatant statement with some very obvious allusions to real-life.
I’m not saying I think your analysis is wrong though, but I’m pretty sure there’s more to it. The droid are more or less treated as the lowest working-class in society. The fact that their not technically people, but still have sentient qualities might be part of the reason many don’t like them.