Indeed, there seems to be a fundamental dilemma there. Satoshi solved the problem of secure trustless e-payments, but there is still no solution for the problem of recovering stolen coins without spoiling that primary goal.
This is unsolvable. Please ponder about the definition of 'stolen' in a system where property is defined by 'knowledge of a key'.
There is no way to mathematically demonstrate that a transaction, for example, was fraudulent. Or that if two people know the same key then one is a rightful owner (whatever that means) and the other is not.
Precisely!
One fundamental flaw of cryptocoins (that supportes consider a feature) is that they are intended to eliminate the notion of "property" for money, and leave only "possession" instead.
You have "possession" of something if you physically can use it or dispose of it as you like.
The thing is your "property" if, and only if, the government thinks you should have possession of it, and you can get his cops and courts to get it.
If a thief steals your car, it becomes his possession; but it is still your property, because the government thinks so, and is expected to take the car from him and give it back to you, by force if needed, once he is found. If your tenant stops paying the rent and refuses to leave, the house is still your property because the government thinks so, and will help you get the guy out. If a hacker empties you bank account, he may get possession of the money, but that money is still your property -- only because the government thinks so. If you fail to pay taxes by the due date, you retain possession of that money, but it will be property of the government -- just because they think it is.
There is no way to define propeprty without reference to some government. If there is no government, there is no property, only possession; and when something gets stolen from you, it becomes the thief's possession, and that is it. YOU (and your friends) may think that it is still your property, but the thief (and his friends) will disagree; what then?
By design, cryptocoins (as the libertarians see them) are meant to be impossible for any government (or any other entity) to take away from their possessors. But then, by design, no government (or any other authority) can enforce any property rights on cryptocoins. (Indeed, early adopters had hoped that the government would be unable even to discover who has possession of the coins; and now that bitcoin has been found to be inadequate in this aspect, they are turning to more sophisticated "truly anonymous" altcoins.)
Therefore, there is no concept of "property" in the realm of cryptocoins. Only "possession".
The notion of "property" as distinct from "possession" is very old; it may have been invented when humans adopted agriculture and settled down, abandoning the "share the catch" economy of nomadic hunter-gatherers. It has become such a basic feature of society that people seem to forget what makes it work.
Do we really want to eliminate the concept of "property" with regards to money?
(PS. And then there is the misleading use of "possession" instead of "knowledge" when talking about keys; but that is another issue.)
All your examples: cars, houses, bank account, tax are non-anonymous. Try again with cash, gold bullion.
Satoshi made it very clear in the title of the white paper: Bitcoin: A Peer-to-Peer Electronic Cash System. Bitcoin is e-cash, not a e-car or e-house.
