They are the agency that is supposed to care but these days they have bigger things to look after and like most other public agencies too few people and too few funds. Back in the day the FCC had shore monitoring stations and they would frequently issue warnings for things like not IDing correctly, operating marine VHF from shore, etc. Today unless they are faced with a specific complaint it seems that they would rather not bother with the amateur and marine bands. The issue with using a radio designed for amateur service on the marine bands is that it could potentially be off frequency a few kHz and cause interference with other communications. In reality that rarely happens and if it does the folks on the receiving end of your transmission will let you know in short order because you'll sound terrible. The licensing requirements for each are completely different. For the marine bands you'll need a ship station license which costs $160 for 10 years and a restricted radio operator permit which costs $60 and is good for life, no knowledge or testing required. For the ham bands you'll just need an operator's license which is free except for a small fee to cover testing costs.