It is the same as when javascript was used to mine cryptocurrency before web browsers blocked it, exploiting other users computers for unfair gain.

Exactly. If there is a legitimate use case for sharing your connection it should be a separate apps users intentionally install.

Sometimes it's botnet, sometimes it's just accessing netflix without hitting big IP range bans.

If there are proxy apps that only do the latter sort of work than I'm actually in favor of them existing and being widespread.

"train our machine to identify traffic lights" or something