> Is the title system in the USA decentralized or that much different than elsewhere?

As with most things both law-related and US-related, it depends. This type of scam would not work in the majority of states due to various laws, regulations, and bookkeeping (it would be nearly* impossible to sell land you don’t own in California for example).

There are other states (and countries - I’m looking at you Canada) where fraudulent documentation and virtually non-existent title checks allow this kind of fraud to persist.

[*] yes - virtually, not completely. It can happen, but the laws are set up such that the land owner will retain their land, the title fraud victim will be made whole financially by a title insurance company. What this means in practice is that title insurance companies make sure every transaction is legitimate and people don’t have to worry about it.