If 5G is all about short distances, why wouldn't people run their own cells? Kind of like running an open Wi-Fi spot.
For technologies that work over long(er) distances, it's -somewhat- logical that you can't put up your own cell tower. If everybody did that, some would stick to standards and some would not. And soon enough you'd have a free-for-all making the spectrum band(s) useless.
And thus we have (some) government regulation on who gets to use the spectrum & how. Auctioning it off to providers who rig up city- or nationwide networks. But what do you pay a provider for:
a) For maintaining the infrastructure. When everybody puts up their own 'micro-cell tower', no need to pay a 3rd party for maintaining it.
b) For connecting it to upstream (wired) infrastructure. But when those upstream connections have to run all the way to your front door anyway, you can do that yourself right? Again, same as in-home Wi-Fi routing to your internet connection.
c) For user-sharing on those networks, billing, network performance monitoring, etc. Again: when it's all short-distance anyway, no need for that, can be done decentralized by end users. Users that don't play by the rules, can only mess with the spectrum in their immediate area.
Yes you'd still need some standards to enable users to move from micro-cell to micro-cell seamlessly. And use the spectrum in a way that minimizes interference for users that are close to each other. But this is mostly a matter of putting some puzzle-pieces together & declare some de facto standards that every user can follow, right? (in the usual case, baked into consumer devices & their firmware).
'5G' coverage would then simply depend on how interested people in an area are in putting up their routers / antenna's etc. Or am I missing something here?