The frequencies are what I was curious about as well. To have a half mile range at relatively low powers it would need to be a low frequency band.

I'm guessing they haven't bought licenses from the FCC, so my bet is that they're using the 900 MHz ISM band.

There's only 26 MHz of spectrum in that band, which isn't much, particularly for a mesh setup that won't be particularly spectrally efficient.

Even with a high 30 dB signal to noise ratio, the Shannon channel capacity in a 26 MHz band is 50 Mbps. MIMO helps a bit, but even in ideal real-world conditions you'll likely have at most 50 Mbps to share between all the users connected to a node. Spread that across a few users/mesh hops, throw in some packet retransmissions and noise, and it's not nearly enough to compete with LTE networks at any meaningful user density.

Incentivizing users to create as many nodes as possible is a good idea, as that allows lower power transmissions and better frequency reuse. It's still a huge struggle to get anywhere near commercial wireless speeds, particularly in areas where there are fewer nodes and a higher density of users.