Re: 2F off
I think that it might also be because most gmail accounts are used as quasi-disposable addresses that the users fundamentally don't care about, certainly not enough to directly hand over their phone number to Google. If it gets hacked, who cares?
Plus, 2FA is rather annoying if you are using a desktop email client. It's bad enough travelling abroad with a laptop connected to Gmail, Google seeming to think it unlikely that a Brit might travel to the far east, or France, and disabling access until you login to their website and confirm that was you. Throw in 2FA as well and then you have to have your own SIM in your phone to receive the code, which for a lot of phones means not having a tourist / local SIM. So you're stuck paying exorbitant roaming charges too.
All in all, I find that Google's security measures truly suck when travelling anywhere slightly more off the beaten track than Dover.