It sounds more fair when you say charge less in poorer countries. However when you turn it around, it is gouge the people in less poor countries.
Especially given that GDP is not evenly distributed among the population. The bulk of the added revenue from technology driven productivity improvements (at least in the US) has gone to the denizens of the C suites and the government, not to the workers. GDP has soared while real-inflation adjusted after-tax income has stagnated or dropped for decades.
That's much of why a nuclear family in the '50s got along fine on a single income and a two-parent family now involves both parents working and the kids in child care, and the bulk of kids are in "non-traditional" family arrangements and/or on some form of public assistance.
So "gouge the developed world's middle class" is indeed what such a GDP-based scheme would accomplish.