I think the intent is baby steps for those who aren’t already privacy invested. Getting parents or tech illiterate to switch to Signal is a win. They weren’t hiding their number anyway.
I currently have a Signal account tied to a sim not in my name. Getting a burner with cash is an option then park it. Or, if you’re lucky enough to live near a payphone and can gain access to the number, you can activate a signal with a phone call.
So easy to setup my tech illiterate parents could do it.
I don’t recall what kind of car it was, but there was one that saved the phone number associated with any phone that connected via Bluetooth.
While I don’t think it’s likely as a way to trick people to connecting to get their phone number, it was a rental car which opened them up to impersonation scams. Knowing they just rented from the company and where in the city provides quite a bit of information on you.
It’s not too difficult to establish a Signal account from a burner number from a prepaid sim card. I currently have a Signal account tied to a sim not in my name. Getting a burner with cash is an option. Or, if you’re lucky enough to live near a payphone and can gain access to the number, you can activate a signal with a phone call.