You may be right, but I get an email every week about FCC enforcement actions and believe me when I tell you that you don't want to be on the business end of one of those.

To be clear, FRS and GMRS radios are only legal to use in the US and Canada. GMRS requires a license. Some channels exist on both FRS and GMRS; you may use those channels legally without a license in the US as long as you stay at or under 500W ERP.

Using these radios in other countries -- including in their territorial waters -- is illegal. I don't know whether it's legal to use them aboard ship in international waters, and I wouldn't rely upon their presence in the gift shop as an indicator.