In my nice first-world country I do trust the government to track it. But in many third-world countries, deed registers are prone to forgery and bribery, and it's not uncommon for people to discover they suddenly don't own their land. I've seen economists argue that this is a major factor limiting economic growth in those countries.
Probably some of those countries would like to fix this, and for them, a blockchain might make sense...say with multiple government entities cross-signing property transfers, rather than requiring all property owners to hold their own keys.
> it's not uncommon for people to discover they suddenly don't own their land
The thing is, the same Government could generally just storm in with guns and say "this is ours now". A known-good register doesn't solve the issue unless you have a separate mechanism of enforcing the register... in which case the solution is filing your deed with the people you trust to enforce it, not using a blockchain.
Also: if you had multiple Government entities cross-signing property transfers, they could just make the lot of it public the normal way, no blockchain necessary. Irrevocability comes from people making copies of the list of transfers.
If you're interested, this is called triple-ledger accounting, you just have to keep all the receipts. This has the advantage that you can keep transactions private until the point that it needs to be made public.
Probably some of those countries would like to fix this, and for them, a blockchain might make sense...say with multiple government entities cross-signing property transfers, rather than requiring all property owners to hold their own keys.