I also have an old account that despite knowing the correct password AND having access to the recovery email for that account, Google refuses to let me log in and there's no recourse. It's frustrating to say the least.
I've also had this situation when relocating countries. I had to abandon a 15 year old account (for which I also had a valid working recovery email) with a lot of issues recovering online banking etc. (Had to physically travel to another country to restore multiple services associated with the account).
I'm with fastmail now. I will never again depend on a mail service that I am not paying for.