You were talking about smart contracts. My answer was about smart contracts I've seen deployed - things like the lighting network and Ethereum's ICO's. If you are saying using the blockchains to manage land-deeds will never work, well maybe you are right. As far as I am aware using a blockchain to directly manage the things you mention hasn't been made to work yet, and to be honest I don't see how it could be made to work.
But using a block chain indirectly to control some of these things seems possible. That's what Ethereum ICO's endeavour to do, and perhaps out there is an ICO out there that works now (I haven't been following). If so it works via the mechanism I described. The ICO turns the "thing" being controlled (CPU Cycles, storage, or whatever) into a tradable commodity which is another way it the flow of the commodity is controlled by money. As you must be aware successful virtual currencies control the flow of money, which in turns means they can be used to control the flow of the commodity. Smart contracts control flow of virtual currencies. QED - smart controls can control commodities.
None of this depends on governments, guns or violence. Instead it depends on there being a market. The reason the value in the virtual currency is secure is because there are lots of people willing to pay for it. The reason purchasing CPU Cycles is secure is because there are lots of people willing to sell you CPU cycles and so a vendor doesn't deliver CPU cycles the customers just move on, the vendor dies but the market continues on happily.
How this could be extended to land-deeds is, as you say, difficult to imagine. But claiming this means "Smart contracts are DOA" is just plain wrong - they work for lots of things, just not the examples you happened to be thinking about.
Nope.
If a normal contract isn't honoured you can go to a judge and ask him to enforce it in some way. It the judge agrees, his decision is then supposedly implemented by the state (police, sheriff of some other state agency) who somehow arranges for the value to be transferred to you - maybe by transferring the value from a bank account, or maybe by forcing the sale of assets. In reality, if you've gone through this process, you will know it's not easy or cheap to make it happen.
In smart contracts the judge is replaced by the mathematics behind the contract. There is no "getting a judge to agree" - it just happens. The actual transfer value is done by the block chain, but the value transferred is not money - it's in the virtual currency. Unlike getting to state officers to their thing the outcome is absolutely guaranteed, totally automatic and free or very close to it - you _will_ get your virtual currency.
The only nit is the value of the smart contract depends on virtual currency being worth money, otherwise it's all a bit meaningless. But if it is worth money something very real has happened - the smart contract has enforced its terms by moving money from them to you. And contrary to what you say, it didn't need help from the state, guns, or anything else beyond the block chain.