I am able to keep customers out of personal space by the design of the buildings. I built my own. In one furniture store I have I put that up front (like separate rooms of complete sets of rooms) but open floor plan. Then closer to the back I put a small table and chairs and the fridge that lets Sims buy food in case they get hungry. Next to that small area are bathrooms for public use. Then I have my Sim's private living space to the west side of the building in the back. They don't follow my Sim anywhere. In the bakery I built living space above it and stairs outside to the side of the building farther away from where they enter the lots. They don't go there, either. And in a clothing store the living space is farther away from what clothes they are supposed to buy. They would have to cross a long floor plan, so they don't go there either. The employee may go to the private areas but that is o.k with me so they can eat or rest or whatever, and then get back to work.
