I don't know why they don't, either, Troodles. Probably because no single country wants to contribute to a global responsibility for all the mess around the world. Did you see that new programme about a globe-trotting English vet? He performs flying surgeries on all sorts of animals. He showed how in India, where 'recycling' means cycling to work and back, goats and cattle are also eating plastic bags by the ton. Literally the ton. The cows' rumens get solidified with the muck, which doesn't break down and soon makes them blow up with putrid gases. He opened up one cow's rumen and proceeded to pull out about 30 kilos of stinking, putrid, muck, all attached to endless lines of plastic bagging. The animal was nearly half the size it had got to after that had been removed.
There's no excuse for throwing all your (literal) crap and rubbish into the streets as is happening in Africa, India, and even the Middle East. I remember visiting some windblown site in a desert in Saudi Arabia, purportedly along one of the famed caravanserais, where one of their ancient poets wrote his verse. The place was a shithole of plastic bags, Coke cans, discarded cigarette cartons and other assorted junk. So much for heritage! The Saudi tour guide didn't even seem to notice it, either, until a bunch of us vented our scorn.
Most of these countries are rich themselves, or, if not so rich, receiving endless millions annually in aid. We can guess where most of the money goes, when we see places like Mugabe's gilded palace, or Chiluba's rows and rows of handmade Swiss suits, made while he took some £63,000,000 of British aid out of Zambia's coffers and into the ask-no-questions Swiss banks. Meanwhile, their people die of AIDS and malaria, their roads cause fatal accidents because of washed-away bridges and pot-holes, and there's no longer any fresh water in villages because the boreholes haven't been maintained.
It's all very well, financially-secure, middle-class Westerners thinking they're doing their bit for the planet by using rope shopping bags, when tens of millions around the globe are filthying it up every day, and dying in the process, while their corrupt government officials withold the money to put it right.
There's pitiful control over the aid, because the countries which receive it pretend they're autonomous, and the elephant in the room is that the West knows they're corrupt, but refuses to withold the aid, as they say 'at least some' gets through to the people. But these countries are as much subjects to dependence, as any of them would've been under colonisation, except that the colonists made sure everything ran as well as possible. Yes, of course, to ensure good standards were upheld for their own welfare, but at least they passed on legacies of education, cleanliness, sewer systems, crop rotation versus slash-and-burn, clean water supplies, well-made and maintained roads, and garbage collection systems which ensured kids didn't play in someone else's faeces, and animals weren't eating filth. The misuse of plastic has contributed a huge amount to spoiling the seas and damaging human and animal health, but no government is sincerely putting their back into stopping it, and many governments couldn't give a damn, as long as their MPs are fattening their wallets.
(If someone sends me a large cheque, I'll stop ranting!)