They want your money as well, though the shop assistants do tend to be slightly more awkward about it.
Only slightly though, as they don’t want to get into trouble with the manager.
The trick is to be confident (easier said than done I know).
If you are fine with it then they don’t have much choice but to just cope.
Once you’ve broken the ice in the big stores it will be fine in the future.
Maybe try shopping away from home where you just won’t give a damn if anyone does give you any grief.
After all, you won’t ever have to go back there.