In Japan, snack bags and food trays may be sorted differently from plastic buckets or toothbrushes. They are all made of plastic, so why are they treated as different kinds of waste?
The reason is that Japan first created a recycling system specifically for containers and packaging. Items used to hold or wrap products made up a large and bulky part of household waste. A system was therefore introduced in which residents separate these items, local governments collect them, and companies that use packaging also help cover the cost of recycling it.
This system applies to things that become unnecessary once the contents have been used. Snack bags and food trays fall into this category. A bucket or toothbrush, however, was not used to package another product. It was the product itself. These items were left outside the original system and were therefore collected as a different type of waste.
In other words, they are not separated because they are made from different kinds of plastic. They are separated because the recycling system was originally built around containers and packaging, while plastic products were placed in another category.
That explanation may make sense on paper, but it still feels confusing to the person throwing something away. When two objects look and feel like the same material, it seems more sensible to collect them together. Many Japanese people find the rules too detailed, inconvenient, and inconsistent from one city to another. Some would prefer one simple nationwide system.
Even so, most people follow the local rules. That does not necessarily mean they agree with them. Their neighbors are following the same rules, and they do not want to be the one who causes trouble at the community garbage collection point. People may complain, but if everyone else is doing it, they usually go along with it. In Japan, it is common to keep following a rule while quietly remaining dissatisfied with it.
Some areas have now started collecting plastic packaging and plastic products together. However, the system is still not the same across the country. In the end, residents usually need to check the waste-sorting guide issued by their own city or town.
Foreign residents should not feel embarrassed if they find the rules confusing. Japanese people also look things up whenever they are unsure. There is no need to be perfect from the beginning. Check when you are uncertain, and make a reasonable effort not to inconvenience the people around you. That is enough.