You are, of course, correct. It is the manufacturers. I hope there's a tipping point soon for all of these companies.
The Mozilla Foundation and others have been scrutinizing these datasets and transfers for a few years
in rather sophisticated ways now, and have been releasing some surprisingly-detailed reports.
It's unbelievable just how MUCH data a modern car dishes out.
And It's not only cars and smartphones, but literally, EVERYTHING that goes online:
AirTags, refrigerators, thermostats, coffeemakers, routers; smarthome stuff like lightbulbs,
outlets, timers, dimmers, switches, garage door openers, curtain rods, pool/hot tub heaters,
stereo systems, ovens, faucets, landscape and security lights, sprinklers, web browsers,
software programs, operating systems, and anything & everything which is a Bluetooth
or wireless or wired connection.
Even my Logitech Harmony programmable remotes, a few years after Logitech
announced the 'complete' discontinuation of the system while also stating that
updates and functionality would continue "for as long as there is a demand,"
has moved the entire system to all of it requiring an online connection.
Such is why I believe they've made it into a data-harvesting system.
The apartment community I live in forced wireless/keypad entry-door locks on each unit
a couple of years ago, plugging their router into a power circuit I pay for.
I immediately signed in to change the codes, then unplugged the router's power
and removed the lock's wireless module after some online research.
This is the kind of dystopian turn things are heading toward.