In addition, GMRS requires an FCC license.[1] Just because the Baofeng allows you to access the frequencies doesn't mean that you can legally transmit on them. I wonder if this is their Capone-tax-evasion-style Achilles' heel. Enforce those FCC regs! :P
Searching on the term linear amplifier, this was the only example of jail time I was able to find, and that after many previous enforcement actions including revoking his license 20 years earlier: http://www.eham.net/articles/1744