Some might agree that membership in the firm is perhaps more compulsory than membership in a municipality, but balk at applying the analogy to the nation.
If something is compulsory, you must do it or accept it, because it is the law or because someone in a position of authority says you must. In East Germany learning Russian was compulsory Many young men are trying to get away from compulsory military conscription. = mandatory + compulsorily com·pul·so·ri·ly Five of the company's senior managers have been made compulsorily redundant. something that is compulsory must be done because it is the law or because someone in authority orders you to = mandatory voluntary