Telling them that a) dealers don’t have access to telemetry data beyond what’s passed on the vehicle data port and b) providing a news article showing that 3/4 new cars communicate data back to the manufacturers unless you specifically opt out isn’t helpful?

Guessing you didn’t actually read the article?

First, you need to differentiate between “dealer” and “manufacturer”, except in minority cases like Tesla, they are two separate entities.

Dealers, as a rule, don’t have the capacity to accept telemetry data from vehicles. Source: I’m a former dealer sysadmin.

What they can and do do, is download telemetry data stored onboard when you bring the vehicle in for service. This is done through the OBD-II port which has been in every car since 1996.

https://www.makeuseof.com/tag/obd-ii-port-used/

If you’re concerned (or curious) about what data is passed over OBD-II, you can buy your own scanner, $20 to $100 on Amazon depending on features.

Now, MANUFACTURERS, that’s a different deal:

https://www.chicagotribune.com/autos/sc-auto-tips-0102-driving-data-collection-20181225-story.html

And, again, what is your definition of “privacy” and what is your definition of “modern car”?

Define “privacy” and define “modern car”.

In the end, it doesn’t matter what car you’re driving if you bring your Android/iPhone…

It may not be “faulty” per se, but if you bought a cheap USB-C cable, you’re going to have a bad day.

USB-C cables are rated for wattage for charging and data throughput.

https://www.pcworld.com/article/395115/the-best-usb-c-cables-for-charging-and-transferring-data.html

If you aren’t running cables with the highest wattage and throughput you can get, you’re not going to get the best results.