They don't have a way of verifying ownership of any other item on the marketplace either. That tablet I have for sale - did I steal it? Maybe. A thief can easily supply a forged receipt. An honest person who bought if for real might have lost their receipt. It's an intractable problem. It's not possible to verify ownership of every item there is. Should online marketplaces simply shut down then? If they are, people will get around it by making buying-selling groups. It is difficult to police behaviour that is, strictly speaking, legal.
If your suggestion was to shut down land sales in Brazil in particular because of the evident failures of the Brazilian government, yeah seems reasonable. Not like it will stop these criminals, but it's a worthwhile step to take.
You mentioned profit a couple of times. How much profit do you think the marketplace made in this case? My understanding is that listings are free.