All of this is true, but it's beside the point. The perception in America is that the rich pay more in taxes as a percentage of their income than the middle class do. The marginal tax rates imply that, with middle class people paying either the 22% or 24% marginal rate, and rich people paying at at 35%+ rate. Thus, people think that we have a progressive system.

However, if you look at the data in this chart, you can see it's not true any longer. The actual combined rate paid by most Americans is between 22-28%. (It's on the lower end for the poorest Americans, and for the wealthiest as well) Fundamentally, the total taxes paid is flat.

I think most people think that the taxes paid chart looks like what it did in the late 70s/early 80s. In that chart, the poorest Americans pay about 20%, and the richest about 45%. That's where we should be, instead of where we are now.

The percent of all taxes paid by the bottom 50% has been going down for the last few decades.

That's an indicator of wealth inequality, no? The top 50% are paying less as a % of their income, but because their income is rising faster (relative to the bottom 50%) than their total tax rate is falling, they end up paying more in total, mainly because the bottom 50% have less to give.

Is that the case if you include payroll taxes? (We could include sales tax too, but those are usually state and local, so we'd then have to add state income tax, and possibly property tax, and that would get complicated)

I’ll go ahead and preface this by saying “I don’t know” but for people at the very top, are there undisclosed tax incentives to encourage them to spend their money?

By undisclosed I mean negotiated. When you are trying to get somebody to spend a ton of money to open a business, donate to charity, bring a bunch of jobs, etc is there a negotiation that happens to provide lower tax options to encourage that spending?

Evidently, as evidenced by every large spending project since the dawn of time (probably?).

As I posted elsewhere in these comments:

Everyone expects a discount on goods and services when purchase in bulk.

Why should taxes be any different?

The wealthy also receive the lions share of benefits from stability and especially international infrastructure maintained by the US state.

Some would argue that taxes are different because of the issue of fairness in society, and for the fortunate who have vastly more than needed to survive, more should be expected to help everyone else. This is in the self interest of the wealthy, as economic growth is actually stunted by inequality.

There are other ways to balance fairness other than progressive taxation, but those too are often anathema to ruling economic policy makers.

I tend to agree with the idea that the wealthy should be taxed more, in a progressive taxation sense.

Perhaps I should have prefaced by previous comment with “playing devils advocate”.

Total income, or "earned income" from a tax perspective?

There's so many technically correct but misleading definitions it's very hard to know what the "real truth" is in these discussions.