They don't require mobile numbers, and setting up a throwaway gmail takes about a minute, not tied to your identity at all. You don't even have to click and activation link, if you pass the CAPTCHA.
That being said, they certainly have IP logs, so make sure to enable Tor.
They've enforced mobile numbers for quite a while now, though I suspect that might be country dependant. I can't sign up for an account without one, through my normal or torified IP (I tried several).
US based, for me, the form element appears, also with country code pre-filled, but it is not required. Further down there is a CAPTCHA that you can elect to complete or tick a box for phone verification. Strange that it's country dependent!
You're very kind, thank you. But you are still incorrect. I cannot register a gmail myself without entering a phone number. Your "workaround" of a captcha does not exist when I try. Others are talking about country restrictions - I live in Canada, if it makes a difference.
That being said, they certainly have IP logs, so make sure to enable Tor.