I'm from that part of the world and laws here are more like "recommendations". It rarely gets enforced until there's a complaint. And the authorities are more likely to be focusing on factories dumping cyanide in a river or bauxite strip mining, rather than plastic nets.

The other side of it is that people are extremely poor. Possibly negative net value, lots of debts and no other way to pay next months bills. These people are going to use whatever it takes to live, and authorities who try to enforce it will look like villains.