Kim you may not like the answer that it is Princess policy but the fact is the do it because they can. Cruise lines will make money anyway they can for their stock holders. It may be a lousy answer but than many things that are done have lousy answers but it doesn't change things.
The only way you will get them to change the policy is by giving them enough complaints and obviously that has not happened at this point.
I agree it is wrong for them to charge the double port charge fee. I do think they will keep doing it because they can and it is their policy.