The US and EU have plenty of landfills, their exporting plastic which was actively separated from the waste stream for recycling which can be profitable. If nobody wants to pay for it then the default is to burn it domestically for energy.
Contaminated recyclables are just garbage. Countries are getting fed up with the EU and US sending supposedly separated recyclables because it's pure garbage falsely labeled as usable plastic. [1]
The issue is the degree of contamination. Different municipal waste streams all have their own internal systems a 98% plastic stream and a 99.9% plastic stream are very different economically.
Completely separate from that it’s a political issue as nobody wants their country to be thought of as a dumping ground. “Malaysia says up to 3,000 tonnes of rubbish will soon be returned to the UK, US, Japan, China, Canada, Australia, the Netherlands, Germany, Saudi Arabia, Singapore, Bangladesh, Norway and France.” what’s not mentioned is this represents 1% of plastic sent to the country. The don’t want to ban the process because the other 99% is quite valuable domestically.