If compromised accounts is the problem, then google could change the authorization on them, and require proof to get back into them. Of course that would require some kind of functional consumer-oriented support line where a human working at google could receive identifying information, check that against Google's internal records and public databases (your old phone numbers, addresses, etc) and check against the con…
This is a highly unreliable, easily gamed non-solution to the problem. If people are determined enough to compromise your accounts, it's easy enough for them to find your old phone numbers, addresses, etc. Websites like https://www.fastpeoplesearch.com/ exist, and it provides generally accurate information on people.
Humans are always the weakest link. If you allow a random person to convince a Google employee that are the owner of the account, they are going to be tricked.
People on HN are always very quick to come to the conclusion that Big Tech not doing something is because of cost, whereas the reality is that the thing HN commenter proposes but Big Tech is not doing is flawed in the first place.