Great.

What do you do when folks in expensive places can't eat while folks in low-cost areas are able to live better?

$100 had different spending power in different places. I can buy more beer in Prague than in Indianapolis. I'll buy even less in Oslo. You often get variance within a country too: A gallon of milk (and a lot of other food) is generally cheaper in Indiana than Hawaii.

I'm with you in spirit - we should tax wealthy people - but not in a way that can tax folks that already are struggling. We just don't have global cooperation like that nor are things starting on equal ground to do that sort of simple taxation. But another comment has already touched on that.

90% taxes on people with only 200% of the median wealth seems awfully excessive. For someone with $16,000 in assets, this would leave them with $1,600 -- just 20% of median wealth. I strongly suspect no tax system in history has ever worked like this.

Not to mention that taxes are collected and spent at the national level, not at the global level. If you are proposing a global government that administers taxes worldwide, that is an interesting idea, but it's not exactly a place to "start" a new tax policy, given that there is no political infrastructure in place to support it and likely couldn't be for decades even if the world made a concerted effort to make it happen.

Complete nonsense unless I benefit from infrastructure and social services from the median country