Someday I'm going to download one of HN data dumps and find the earliest mention of this particular scare story. It must be ten or even fifteen years old by now, ever since Amazon started offering 3G equipped Kindles with an always-on connection.

Sneaky cellular access hasn't happened so far, not because the vendors wouldn't like the capability, but (IMO) because it would introduce enough of its own costs and complications to be unprofitable. It's easier to piggyback on customers' internet and disregard the small fraction of privacy-conscious buyers.

This is the actual reason there was all that hysteria around the "race to 5G" with the dire warnings that we'd be buried by China if we didn't roll out 5G ASAP. The actual reason is that 5G works better with congested cells and large numbers of clients than 4G, so it's a lot easier to put cellular modems in every device and bypass those pesky users.