Why does this keep happening?

Simple.....because there are humans in the world. No other species mindlessly destroys and pollutes the environment that sustains it.

Because the world is full of greedy, selfish, corrupt and irresponsible people..

You have to ask, how did the nets get there in the first place. All nets should have a code in the material so their owner can be identified.

As long as humans are here, everything else is in danger.

Chyna predatory fishing

Very tragic, thanks to all the good humans out there.

Chinese abandoned fishing nets, they're the heavy users of this kind of commercial nets.

A lot of illegal fishing, and local or stategovernments either choose not to enforce the law or don't have the resources to enforce anymore. And if they do, local police is, by virtue of low pay, often taking bribes just to let it go.

Well done. Congratulations!