Taxes have massively increased over the last hundred years everywhere in the West. As the poster above said, there are large network effects and switching costs (border control and visas as well as actual relocation costs and language/culture barrier and losing family and friends) which practically prevent moving for most people, even if hypothetically they'd prefer to move to a lower tax location. This, coupled with the small number of countries, makes for a dire situation for international competition between countries to lower tax burdens.
It's the same reason crypto exchanges can get away with exorbitant fees. Nobody wants fees but the network effects are too sticky. So everyone pays the fees.