Don't we need to know the purchasing power of money in the country? Without that the median wage is just a number and it doesn't tell anything about standard of living and such. We only get to know how many foreign products they can afford in dollars. And not even that because import tax varies, too.

And last time I looked, Japan had lik 8% or 10% VAT. And I believe Poland has 23%. So immediately all goods are way more expensive and it doesn't really compare.

If you have an idea about the Japanese economy that predates 2010, you probably want to look into the situation again. There were many changes under Abenomics that significantly worsened the situation for the average worker, and therefore for the average family.

And in the last year or two, the cost of living has gone up significantly, but for the most part wages have not risen to match it.

The following table represents data from OECD's "median disposable income per person" metric; disposable income deducts from gross income the value of taxes on income and wealth paid and of contributions paid by households to public social security schemes.[4] The figures are equivalised by dividing income by the square root of household size. As OECD displays median disposable incomes in each country's respective currency, the values were converted here using PPP conversion factors for private consumption from the same source, accounting for each country's cost of living in the year that the disposable median income was recorded.[5] Data are in United States dollars at current prices and current purchasing power parity for private consumption for the reference year.

It should be noted these numbers are in no way indicative of standard of living, as someone in a high tax country with excellent services may appear to have lower income despite having fewer expenses after taxes.

On the other hand, the inflation rate in Japan has averaged close to 0% for the past 30 years. Japan used to be considered an expensive country, but now I think it's safe to say that it's cheaper than much of North America and Europe