That's a big problem with "smart contract" systems. The "trustless" part only works if you stay within the smart contract system. About all you can do with that is speculate in various crypto items. The ties to the real world are weak. Yes, there are "oracles" for widely available non-controversial info, such as the DJIA. But how do you get an oracle for "house is complete as specified and is ready for occupancy"? Or "package was delivered and contained contents as ordered"?

In systems where transactions are reversable, such as credit cards, problems can be fixed up later. But with instant irreversible transactions, you don't have that feature.