I am a young person who has never sent a fax so please forgive my ignorance, but how does a fax allow you to prove you sent it? edit: nvm I looked it up myself

I am a young person who has never sent a fax so please forgive my ignorance, but how does a fax allow you to prove you sent it? edit: nvm I looked it up myself and learned about fax receipts. Sucks that the equivalent feature in email (read receipts) is usually not enabled due to abuse by spammers.