Why should that obligation be proportional (or progressively proportional) to the wealth you have and not to the resources you use (or wealth you have in that country). Why someone who made millions in Poland (and paid taxed there) should pay 20x for living the same life in say Spain as a typical resident there?

It's so easy to say "moral" but I struggle to see the moral principle at play. I understand paying proportionally to resources/wealth in that country. I understand paying progressively for those or income in that country but why pay in proportion to what you have already build in another place?

> Why should that obligation be proportional (or progressively proportional) to the wealth you have and not to the resources you use

It is proportional to the resources you use in every case where that is possible. It is nonsensical to say "Well, you used only 2% of police time this year, so that's how much police-tax you'll be paying", not least because it is impossible to put a "usage" on the benefit of having police in the first place. Where it is possible, like how much land you own, you are taxed proportionately.

Live in that other place, then, mate.