I will just remind you all that “average salary” is the place where people earning 1,000 and people earning 50,000 meet, and tells nothing on how many people earns each.
Take Spain, FAI, gross salary in euros per year (2017):
Average salary: 23,156.34 €/year
Median salary: 19,432.62 €/year
Mode salary: 16,497.40 €/year
Average salary: sum of all salaries divided by all employees Median salary: half the salaries are higher than this salary and half are lower than it Mode salary: the most frequent salary
This means that in 2017 half Spaniards had a salary that was at least 16% below the average, and the most usual salary was 38.8% below the “average” salary.
If you ask the common folk in Spain and tell them that their “average” salary is 23,000 a year they will say “bollocks”.
I mentioned one or two of the things rich people can do to make income non-taxable. Even so, IIRC in “first-world” countries mean income is usually skewed upwards by high-income individuals (a simple (but not 100% reliable) indicator for this is the difference between the mean and the median).
It varies by country though.
And it can be done in other ways: someone looking to manipulate the statistics has many ways to skew them (like including/excluding people on state pensions)
There’s also the “shadow/untaxed/invisible economy” to consider. It’s significant even in many “first-world” countries. Some countries estimate it, some don’t. Estimating it is good, but it means there’s a lot of cash available for a statistical cheat to use as a “slush fund”.
In general I don’t think you can trust a surface analysis (like comparing mean and median) to draw conclusions you can be confident in. And my recollection could be wrong - it’s been a long time since I was current with this stuff
