Yes, anyone can tune in to listen to ham radio, but it's important that we have parts of the radio spectrum to ourselves, otherwise all frequencies from DC to daylight would be licensed for commercial and public safety (much of which isn't listenable without buying horrifically expensive gear, if it isn't completely encrypted for no reason other than to eliminate transparency) use. US.gov doesn't really make much from ham radio, and could easily say "fuck it, this is worthless, time to make some money, bye hams".

The only fees they collect are for the radio equivalent of vanity license plates; vanity callsigns. To get a randomly assigned callsign is free, but most of them are hard to copy under poor radio conditions, so some of us get vanities. Currently they're $16.10 for 10 years, but the FCC is seeking to increase it: http://w6sg.net/site/?p=1270