As with most ad valorem (or fixed per unit) consumption taxes, because consumption as a share of income declines with increasing income, so total and marginal tax share drops with greater income.
> Yes, like every sales tax, VAT, etc used everywhere around the world except for super liberal places like Montana.
Yes, sales taxes and VATs are regressive, though in many cases that is made somewhat more nuanced by selective exclusion of basic necessities on which the poor focus a disproportionate share of consumption; when that's done, they are progressive at the low end shifting to regressive higher. This kind of tax that puts it's heaviest burden somewhere between the above average income segment of the working class and the petit bourgeois middle class is somewhat more popular than straight regressive taxation (when you take into account payroll taxes and favorable taxation on LTCG and certain other income disproportionately concentrated among the very rich, US taxes on income also largely break this way).
> Calling these taxes regressive just a socially acceptable way for people to say “I don’t want to shoulder any burden for this”.
Er, no. I actually favor heavier gas taxes (or carbon taxes) as a pigovian tax, but I think that the overall system of taxation should be asjusted so the net effect is not to to decrease progressivity (which, given that I have above average income, probably means I shoulder the burden of that as well as of the additional gas tax, so really the opposite of what you suggest). An individual tax desirable for other reasons being regressive is an addressivle issue.
I'm not sure that's true about consumption in general?
But in any case, I don't think it matters too much whether individual taxes are progressive or regressive or flat. That consideration only really makes a difference for the overall tax system. Individual taxes can be designed to be as efficient as possible, as long as the overall system is as progressive/flat/regressive as desired.
