I don't even think its the car. I can't recall a phone that made calls by being plugged in.
It's down to a combination of OS on both the phone and whatever the car is using to communicate with the phone.
I have an incredibly vague recollection of there being some phones that supported USB as a hands-free connectivity method, but we're talking about a seriously tiny number of models that are from around the dawn of time for Bluetooth first appearing in cars. At this point, that's 20-plus years ago, and in a modern context even wired Carplay and Android Auto used Bluetooth for handsfree.
Detecting nearby bluetooth devices is not the same as connecting to them. The phone will not connect unless you have given it permission.
True, but there is a corollary to that. More:
Having bluetooth enabled is not a security risk.
Saying that enabling it is not a security risk is dangerous: it disregards the possibility of an unpatched or not-openly-known vulnerability being exploited. There have been vulnerabilities in Bluetooth stacks from the physical layer on up over the years, and while that hasn't happened frequently, it has happened. With this in mind and security best practices being what they are, switching things off that aren't vital to intended use is generally the right call.
Now, do I leave it switched on on my phone 24/7? Yep, pretty much, and I accept the potential risks that go along with that. But the
@clunker71 is in charge of how he chooses to use his devices since he's the only one who knows the environment and use cases they're placed in. Can't really fault him for taking an active approach to his security posture since ultimately it doesn't affect anyone else.
As a general comment, one good reason for disabling Bluetooth is privacy.
Retail establishments love to track footfall via Bluetooth - and that New York Times article is from six years ago. This has been happening since about the early 2010s, really picked up steam after roughly 2015, and is now an exceptionally efficient aggregator of customer movements both in and between properties (i.e., stores) as well as a passive correlator of spending habits, demographic information, and so forth.
Ain't living in the future just grand?