It has been a while since free “single-use plastic bags” have disappeared from big supermarkets in NSW, Australia. Apparently, “plastic bags” are so bad for the environment that they had to get rid of them and instead we now have to pay 15 cents each for much tougher “plastic bags” if we don’t have any bags to carry our grocery! What’s the diff?
Anyway, what do you call “single-use plastic bags” in Japanese?
I heard the words “plastic” and “bag” caused a chaos in court a few years ago in Japan. An English speaking witness to a robbery testified in court that the robber was carrying a “plastic bag” and the word “plastic bag” got translated as プラスチック製（せい）のカバン which sounds like a hard-case made of plastic, but the bag the robber was actually carrying was what we call in Australia a “single-use plastic bag!” so you can imagine how confusing it was!
There is no official name for “single-use plastic bags” in Japanese but most common words are either レジ袋（ぶくろ）, スーパー袋（ぶくろ）or ビニール袋（ぶくろ）.
If you use the word プラスチック, it usually indicates something solid. The material in question here is probably NOT “vinyl” but in Japanese soft plastic is usually called ビニール.
カバン is also something solid. Soft bags are usually called 袋 and it is read as ふくろ on its own but if other words are used in front of it, as shown in the examples above, the pronunciation usually changes to ぶくろ.