Truckers are the 'intended users' of CB? Truckers took up using CB long after the FCC took 11 meters away from hams and enacted the original 'CB' band. It wasn't called the truckers band, after all. CB was meant for the general citizenry to have access to a radio band for enjoyment and short range personal communications.
The uses that truckers put CB to were originally to keep long haul truckers alert and awake during their driving stints. Then it was for them to keep each other informed about driving and road conditions, then to warn each other about police activity--or 'smokie reports' as they used to be called. Then companies with loading/unloading facilities got into the picture and started using the CB frequencies as an easy way to get truckers to their assigned docks and doors to back their rig into to unload/load.
Now it seems that the truckers are the predominant users of the CB frequencies, at least here in the US-- especially on channels 19--the general road frequency, and 9, the CB 'emergency' frequency. The upper frequencies, channels 30 to 40 are used by sidebanders most of the time with the rest used locally by whoever wants to use them--these days hardly anybody. The FRS radios are more popular now for good reason for those who want short distance comms.
Now to enforcement. A local man (in my area) was brazenly open about his CB uses--including high power transmissions--with the belief that the FCC couldn't be bothered. Well, he was active for about 2 years--till the day when the FCC, the federal marshalls, and the state police paid him a visit. They confiscated ALL of his radio gear, cut coax just about wherever they found it, pulled down the antennas he had up--including on his van--and slapped him with fines totalling in excess of $10,000! It turns out that they had over a years worth of recordings where he identified himself and his location and brazenly stated--many time--that he couldn't care less about the 'feds.'
The FCC listens to complaints--and to the bands about which the complaints are made, and takes action if the situation in their opinion warrants it. If you want to read more, google 'FM broadcast band pirates' to see what they do to unlicensed FM broadcast stations, especially in Florida. 73!
The FCC has really gone after FM pirates. Here in Northern California, where we had a HUGE illegal FM scene in the 90s, the FCC has licensed so many legal FM stn's in San Francisco and Sacramento that they've virtually eliminated "dead air" on FM, and squeezed out the pirates. It used to be I could hear San Francisco, Stockton, and Chico on FM from my Sacramento QTH, but no more. It was a genius move from the cops' perspective, the only problem is that now we have too many FM stations for the population, and they beat each other over the head for a 1.2 rating.
As I said, the FCC will go after flagrant violators. Publicly thumbing your nose at the FCC is guaranteed to get you a visit-don't wake Smokey Bear from his sleep! Interfering with VHF, like the guy in Merced, CA who was knocking out his local fire dept's 2m freq, is another way to get caught.
My dad bought FRS radios for use around the house, the only problem is, the freqs are so crowded that you can't find any dead air. Today he uses my old toy walkie talkies from the 80s, I think they're GE System 3's and operate on 6m.