Sports betting verification: why do some books ask for your life story

Trying to withdraw from a couple different sites and some are cool with just an ID pic, others want six different docs, a selfie holding your ID, a copy of your utility bill from three months ago, and a written note saying you love their terms. Seriously, it feels like applying for a mortgage, not cashing out some winnings. Always wondered if there’s an actual standard for this or if they just decide how tough to make it based on their own risk or whatever.

Does anyone know if they’re trying to stop fraud, keep out pros, or just make it a pain to withdraw so you leave the money sitting? Wondering if anyone else has found a book with a more “statistically average” verification process.