Earlier quoted context omitted.
In the 1940s sweaters were american made, did not cost $400, and the median american had more disposable income than now. The people who benefitted from outsourcing were those buying shares, not sweaters.
If you think the median american had more disposable income in 1940 than today, you are hilariously uninformed. https://fred.stlouisfed.org/series/DSPIC96 (only goes back to ~1960, and the I think this is mean, not median, but also a huge enough trend that it is impossible to deny).
What does it mean that 2020 shows 15K average disposable income in the US? That the average person has 15K left once they pay absolutely necessary to subsist? I find it hard to believe.
I think most people using the word "disposable income" would use the term the way I stated. Also the post you reply to uses it in that sense, not as a relative value to taxes.
I believe this graph shows something different altogether, it simply shows wages - taxes. It has no bearing as to the purchasing power of that salary and what you could afford with it.