Are people in prison allowed to sign into their Google accounts? I imagine they wouldn't be able to bring 2FA or even a list of backup PWs with them (unless memorized in advance)
If it's so important to them, maybe their partners or family can login - or they can do a takeout and store their data in a hard drive. Who knows if Google services will be around when they get out, right?
Sometimes I am not even confident they'll be around tomorrow.