You dont need your old wallet to travel ... just get a new one ... Mommy or Daddy could have got a cheap one from Walmart ...
He doesnt need a phone .. He wouldnt be contacting Mommy or Daddy for a while ...
They have plenty of money ...they could have bought him new ID so he could get on a plane ...
It isn't about a wallet but about what's in it, like ID.
It was probably left behind to throw off Leos.
As I stated, he probably got a burner phone.