Mos Eisley is a popular place, so the shop being full isn't terribly surprising. If it persists for more than a day or so, it might be the case that it is full with inactive players, for which the assistants would have to be called in to relocate them.
I dare you to make less sense.
Are you a newbie, or do you have access to newbies?
I had the same problem with that same shop over a period of 2 days recently (last weekish?). I left without a successful visit. ("Jawas! Your Jawas! We don't serve their kind here. They'll have to wait outside.")
A fellow player also reports the same problem with a facility on Csilla (I think, wherever Chiss spawn.)
I wonder, do hired NPCs that get abandoned there add to the passenger tally? Could it be mostly NPCs?