California Civil Code Section 5600 (b) which is part of the Davis-Stirling Act reads as follows: 

An association shall not impose or collect an assessment or fee that exceeds the amount necessary to defray the cost for which it is levied. 

Consequently, an association cannot charge a move-in or move-out fee without violating the law. Notwithstanding, an association can demand that a refundable deposit be paid to cover the possible cost of damage to the common area when someone moves in or out, assuming the association's CC&Rs or operating rules permit the collection of such a deposit.