Being an Assistant Language Teacher (ALT) in Japan used to be a prestigious job. It was government funded with high infrastructure and support. But since the mid-2000s the government had started to source for teachers from the private sector.
During its heyday an ALT would earn a minimum 300,000 yen (USD2,639 as of writing) as the basic minimum wage. Somewhere along the way the government had discovered that it was cheaper to outsource and that people were willing to work even at this low salary.
But what happened then is that the quality of the teachers employed dropped dramatically, leaving schools to pick from a smaller and below average pool. ALTs were from the beginning not good anyway, as they were never qualified to be teachers in the first place. A bachelor’s degree is all you need. In this sense, then, the salary reflects this. I do not think some ALTs are worth the original pay minimum because they were not qualified to even be assistants. Their area of study was not that of English. What qualified them was that they were native speakers and nothing else. Most had zero training and even if they have an interest in the English language their competence is not that high.
Below is a video which explains just how much an ALT can have on a months salary at the current pay level. I feel for them on this one.