I remember when phones used to be good.
Telemarketers have been around for a long, long time (Wikipedia claim "...the practice of contacting potential customers by telephone originated in the late 19th century.").
I personally recall a lot more telemarketing in the 90s, though I was a kid and just passed the phone to mom or dad. But that was also a time when caller ID was a luxury, and not everyone had answering machines.
I think a lot of companies view their free plan as recruiting/advertising
if you use TailScale personally and have a great experience then you'll bring in business by advocating for it at work.
Of course it could go either way, and I don't rely on TailScale (it's my "backup" VPN to my home network)... we'll see, I guess.