So, they sign on as a deckhand and then jump ship in a convenient port. Just say (as has been said) it is for game play reasons
I do think, however, that we should look into taxation for adventurers again. I think on tax day they should be taxed by whatever region they happen to be in on that day, in addition to the realm taxes they already pay.
I can think of a million ways I'd rather see the dev team spend their time, personally. A million unfinished features. A million things that would add more fun to the game, instead of just taking 10 gold from advies every month.