I have two accounts I used to use for a personal map that got captchas all the time...no warnings playing legit on a phone. One account I bought on eBay dirt cheap, clearly bottled and getting warnings.
My own bot account got warnings, which went away after 30 or so days, I play it legit now and no warnings.
My 100% legit account has never had a captcha or a warning, nor have any of my legit friends accounts.
I know that's only about 20 accounts total, but I think that's representative of the people here too. For the most part, they seem to have a good algorithm for flagging non human players right now.
Always fun to watch as time goes by.