giving lost stuff to the police is fairly standard practice where i am at least
I thought it was common practice everywhere.
Like, if you found a wallet with cash and cards in it, you'd hand it in to the police.
Only time it's not necessarily useful to hand something in to the police (in the UK at least), is if it is a Passport.
Because Passports that are lost and handed in legally have to be destroyed, not returned to their owner.
If you can manage to return the passport to its owner by yourself then you're saving them time and money.