Re: Is this how far we have sunk?
"surely they would need to return (especially since charges were dropped) anything they confiscated, in same condition they were when confiscated."
Not in NZ, and not in the Netherlands.
If the Dutch police search your car for drugs (ie take it to pieces) and don't find any, they will return the car in pieces.
As long as they had legal grounds for a search, and they followed the rules for evidence preservation, then they are covered.
If they only do it to you every three months it also doesn't meet the threshold for harassment.