The device known as shoyu-tai (or soy-sauce snapper in Japanese) was invented in 1954 by Teruo Watanabe, the founder of Osaka-based company Asahi Sogyo, according to a report from Japan’s Radio Kansai.
It was then common for glass and ceramic containers to be used but the advent of cheap industrial plastics allowed the creation of a small polyethylene container in the shape of a fish, officially named the “Lunch Charm”.
The invention quickly spread around Japan and eventually worldwide, and it is estimated that billions have been produced.
These companies use plastic because of its weight and ease of manufacturing and I assume it’s also cheaper than glass. The weight may seem a weird metric but when they are shipping billion of them every year it adds up.
If they were forced to change to glass they would definitely increase the price to compensate.
I would love to save the world from ecological collapse, but not if I have to pay for it in any way shape of form whatsoever!