Actually, wireless ISPs are very common around the world. Yes, line of sight to another node or a tower is always necessary.

There's such an odd divide between tech geeks who like to sit around and think about "p2p wireless decentralized mesh networks", and don't know of any network that doesn't use those buzzwords, and wireless ISP operators who actually build them in the real world despite never having heard the word "mesh".

Generally the networks started by the mesh geeks perform much worse, and have few, if any subscribers, despite the fact that topology and equipment are identical to a wireless ISP.

Source: was a mesh geek, started a company making open source software for p2p mesh networks, now it serves wireless ISPs, who tend to have 100x the hustle and professionalism of the mesh geeks.