This is an irresponsible presentation of the data. I’ll wager that a consistent takeaway on seeing this is that American’s don’t pay taxes the way other countries do, that taxes aere pretty low.
There is, of course, some truth to this; average taxes for Americans are lower than average taxes for Europeans, and there’s a corresponding lack of fundamental social services like education and health.
But to express collective tax as a function of collective GDP is misleading. It doesn’t take into account that the burdens of taxes are often deeper for the vanishing middle class than they are for the diminishing number of people who hold an increasingly large proportion of the wealth. Were the super-wealthy taxed as they were before the Bush tax cuts, taxes would be a much larger % of the GDP, and I wouldn’t argue with that.
Tax Revenue as a Percentage of the GDP in the Developed World