Meshnets only work in high population density areas.
Why? Is this a limitation of hardware generally available, licensing is required for high enough powered transmitting devices? Or what?
Meshnets don't use high powered transmitters. They depend on non-licensed freqs.
Okay. I assume you mean
current meshnets. Are there no open frequencies that can be used for long distance communications?
Because yeah. It seems a true centrally-owned-infrastructure-free dream cannot be had if there is a monopoly on long distance comms, as you said.
Antennas using 802.11n have been able to achieve transmission distances over 300 km unamplified.
Well that is more interesting! If something like this could be used to link cities.
I'm guessing that terrain matters though and this "300km" was line of sight?