How did you know that it was phoning home from a test drive?

There's a story someone wrote in a comment or otherwise posted here about Tesla telemetry identifying an employee who crossed one of the SF bay area bridges at 130mph

The Tesla salesman told me when I asked.

What would be the motivation for Tesla to "snitch" on their customers and kill sales?

Legislation requiring them to do so. If they have the capability, eventually law enforcement will start asking for the data. If Tesla don't provide the data, you get a lot of headlines about how police are unable to solve hit-and-run cases etc. because they're not getting data that's just there for the taking. Cue legislation.

Then all car manufacturers would have to as well. (Tesla is not the only car that "phones home", others do as well, and increasingly so.)

So, to avoid this type surveillance, you would need to forego driving, which is completely your choice. However, this is not merely a "Tesla" problem.

Sure, fully agree. I didn't mean to imply it was just Tesla's issue, it's an issue with "Smart tech" in general, which was the topic at hand.

Cops asking politely! If you've done nothing wrong you've nothing to hide, etc.