If adding telemetry is faster and easier than engaging with the customer, then you'll see projects that add telemetry that wouldn't otherwise have the bandwidth to engage with the customer.
In general, I think the best way to go is to ask in the installer or initial setup, whether you want to send telemetry, and have a sane default according to whether you gather potentially personal information (location? personal, commands run (without args), not personal).
Example Prompt: Send telemetry (commands used, version) (y/n)[y]:
An additional flag for non-interactive installs can solve the problem, but that's a broken setup experience, someone has to look up the documentation after a failure to install.
Turning it off by default in case of a CI/CD setup means losing most of the data.
I'd recommend a required installer flag forcing the user to make a decision, but I'm a user who generally leaves telemetry on.
Here's what we are doing next release (out this week)
* Ask if the user wants to opt out in the graphical installers.
* Print a message after non-graphical installs about data collection and link to documentation on how to turn it off.
If you get an uptake of say 5-10%, if that's worth it then problem solved. If it's not then don't bother adding telemetry to start with.
But before you do this, you have to ask the question: how did the software industry get by before the sudden rise of telemetry? It engaged the customer.
I think a lot of cases it is used it is used as a substitute for engaging the customer.