According to the studies I found online, the Philippines generate the most plastic trash that makes it to the oceans. They don’t produce the most plastic waste, that distinction belongs to the US. But we manage our waste better.
So what contributes to this situation? One thing I can see is that everywhere in the Philippines is pretty close to the water.
https://worldpopulationreview.com/country-rankings/plastic-pollution-by-country
https://plasticbank.com/which-country-is-the-most-accountable-for-ocean-plastic/
There is an explanation in your first reference:
While many high-income countries generate high amounts of plastic waste per person, they are also typically better at processing it safely, whereas middle-income and low-income countries still developing their infrastructure tend to produce a higher percentage of mismanaged waste plastic, which is more likely to find its way from land into the ocean.
The Republic of the Philippines is both a developing low-to-medium-income nation and an island archipelago, so they generate a lot of plastic waste, don’t manage it well, and almost everything you don’t anchor down winds up in the water.
We were just at the Museum of Science and Industry in Chicago, and saw a very interesting exhibit on plastic waste accumulating in the oceans. We were surprised to learn that the top three sources in the Pacific were all in the Philippines. Ugh.
Publicly funded trash collection is very rare. Where my Winter Palace is the local garbage truck has been broken down for years. If you bring your bagged trash to the local government offices on Tuesday morning they will take care of it but most people burn it or dispose of it on a lonely roadside. I’ve heard that for the equivalent of aa few cents some fishermen will take your garbage and dump it in the ocean.