There’s also nothing stopping any of them from including an Iridium modem in their sets. Or using aircrack to try and break into a nearby network. Or any other tinfoil hat thing we can come up with.
There are literally thousands of paranoid security researchers who would love to post about something like this (hi), and none of them have. That’s hardly conclusive, but if it’s not good enough for you then maybe you should reconsider whether society is the place for you.
I'm sure they're not doing it now, I'm not sure they won't do it eventually. I don't think it can be done without people noticing but I'm also not sure they'll think that far ahead.