Re: they definitely do IP address tracking
"Not only Netflix. Gmail, for example, treats frequent IP address changes as suspect*"
Which is why I gave up using Tor for gmail. I use a proper email client not their web front end, and have fetchmail log into gmail every couple of minutes to see if I have new email. You can imagine how Tor would trigger an gmail complaint email every couple of minutes. Though I guess that would ensure there is at least one email to collect each time.
I'm going with another fix for that problem, weening myself off gmail.