There are two things you need to consider. What you do with this information is up to you….
Radio service licensing:
There are two types of radio services that apply here. Licensed radio services that require an FCC issued license to transmit, and license by rule, that do not require an FCC issued license, however there are certain requirements that must be met.
GMRS requires an FCC issued GMRS license to legally transmit.
Amateur radio (ham) requires an FCC issued amateur radio license to legally transmit.
If you do not have a license, you would technically be in violation of the rules for those radio services.
Equipment type certification:
The FCC issues type certification for different types of radios. Type certification ensures that the equipment is designed to work properly on specific radio services, and usually requires some safeguards to prevent 'undesired' operation.
Radios transmitting on the GMRS frequencies require Part 95E type certification.
Radios transmitting on the MURS frequencies require Part 95J type certification.
Radios transmitting on the FRS radio service require Part 95B type certification.
Radios transmitting on the amateur radio service do not require type certification on the transmitters.
If the radio you are using does not have the correct FCC type certification for the radio service you want to use, then that is technically a violation.
Some of the type certification rules negate other radio services. FRS requires a non-removable antenna.
MURS requires only MURS channels in the radio.
Amateur radios are not permitted to transmit anywhere outside the amateur bands.
So, a lot of these Cheap Chinese Radios cause issues because they can be made to do things they shouldn't. The Chinese don't care about FCC rules….
For GMRS, you also need to look at the Line C rules. There are specific GMRS channels that are not permitted that close to the Canadian border. It's an old rule, but it's still on the books.
It's important to understand all the FCC rules and how they apply to the radio services you are licensed for.
Now, to be honest:
The FCC doesn't fly around in helicopters with swat teams on board just waiting for someone to accidentally key up on the wrong frequency. Most of this stuff is a trust thing. The FCC trusts you'll do the right thing with your license. Some individuals can be trusted, some cannot.
Many will argue that the rules don't apply to them, or there are variances given. FCC rules disagree. People who use those arguments are just trying to justify either not knowing what the rules are, or not caring what the rules are.
A lot of these radios can be opened up to do things that are not technically legal. That doesn't mean the rules no longer apply. It just means the burden is on you to understand what you are doing and to not cause any issues.
Like I said above, what you do with this information is up to you. Most of us don't care what you do with your radio just as long as you don't cause issues for other users. Just keep in mind that the rules are there for good reasons, even if you may not fully understand them.