He's most likely registered at his parent's address, but it's not like there's an age restriction where you're no longer allowed to live in your parent's baseme

He's most likely registered at his parent's address, but it's not like there's an age restriction where you're no longer allowed to live in your parent's basement or to physically be there ;) At that age he's also mostly included in his parent's insurances, so one less thing to worry about. Taxes are deducted automatically from his wage. And to receive the wage he just needs a bank account.