Sociology to be precise, but I get what you mean. :slfg:
Long story short, in an ideal world importing stuff privatly should reduce the retail price of things, bringing more customers into local shops to spend there money on shore. and in doing this it should also bring more job oppurtunitys to locals and local business people. However in the real world people bringing in there own goods does the opposit. retailers go hey we are not getting enough money now so insteed of lowering our prices to make more sales for lower profit we will raise our prices to make higher profit on less sales. and because they are not selling as much it means that there is less work available for people and so on.