I love your visual walk through history. It's important to note that it was the same people living in the analog world who adopted the digital world, in turn giving the digital cities the power they now have.
It's not so much the government *couldn't* collect much tax, but that they weren't agressive enough. But other fees, coupled with consumers wanting everything cheaper, drove many industries to other countries, taking jobs with them.
All the digital cities taking percentages? That's no different than the analog cities taking all the brick and mortar fees. In the end, though, the fees through digital cities is cheaper. The lower cost to being completely online is something often forgotten and overlooked.