A friend (really, a friend) defaulted on several student loans but was
never contacted directly by the collection agencies or loan
authorities; his family and friends received various threatening
letters addressed and directed to him at their address even though he
never lived there at all or hadn't lived there in years. They
received no court summons that he knows of. They never revealed where
the friend was living and he never got garnished or contacted
directly. It was in a state that allows garnishment of wages for
defaulted student loans without a court judgement. He moved to
another state years ago. He's unemployed now but has some savings.
If they ever catch up with him, would they be able to garnish his bank
account in his new state without a court notice and without sending
him a letters or dragging him into court? In other words, would he
know first that they found him so it would give him a chance to
withdraw those funds first? Can they garmish bank accounts without
court orders or can they only garnish wages? What about tax refunds?
Is this garnishment-without-court thing only allowable if you're
living in the same state where you took out the loan or is it
allowable anywhere?

If people know, can you cite specific laws about either answer rather
just than a Yes or No? Either way, any answer is much appreciated!

It all varies by state. What state?

If the creditor tries hard enough they will find the saving account.

There are bank account locating services, accounts that pays interest
are the easiest to find because of IRS reporting.

Usually before a garnishment is placed, the debtor is given a chance
to claim an exemption (money is frozen). If you can prove the money
is from exempt sources, i.e. disability payments then the bank has to
unfreeze that portion. If the bank does not hear from you within 5
days the money is gone. Best advice keep the money out of the bank.