This is basically what wifi, bluetooth, and garage door openers use. The sad thing is that they carved out chunks of the spectrum that don't reach as far as the already-in-use TV and radio spectrums. We get the leftover bits for arbitrary consumer transmission, the good parts are spoken for by corporations with deep pockets. I'd like to see the whole thing opened up, it would make meshnets easier to get going.
>We get the leftover bits for arbitrary consumer transmission, the good parts are spoken for by corporations with deep pockets.
Actually, no. Check out a chart of the usage of the radio spectrum in the US, and you'll find a shockingly huge amount of it is reserved for the military.
If you look at the spectrum, however, the deep-pocketed corporations are only getting preference of a very tiny sliver of the spectrum. They should be getting preference, because they can do a lot more with that spectrum than the rest of us can. I hate to argue for deep-pocketed corporations, but it's true: we simply wouldn't have things like cellphones and 4G without them controlling the spectrum this way. You can't have things like that with massive amounts of interference from amateurs broadcasting whatever they want with low spectral efficiency (the spectral efficiency of old analog stuff is terrible compared to modern protocols). You can't legislate the laws of physics; there's only so much spectrum available.
The solution, to me, is simple: if the little people want to be able to do more with the radio waves, they need to get the government to release some bands to them for amateur or low-power use, instead of expecting everyone to cram anything and everything into the 2.4GHz band. There's a huge amount of spectrum out there, but we're not allowed to use it because it's reserved for military radios. The military doesn't need to control the vast majority of the spectrum; it's not like they're exchanging vast quantities of data with it, the way we civilians do with our phones.
Probably a lot of bad actors would show up. But who knows? Maybe most of them would get bored and leave.