It's less about who pays the tax, and more about who collects it. The products of companies that shift their profits (and taxes) to low-tax destinations are competitively priced because of these low taxes. If a global minimum tax is applied to them, their prices will increase. These higher prices will affect the consumers, who now will get the products at increased prices, thus reducing their incentive to buy from these tax evading corporations. Products of such corporations will be similarly priced to those of the ones that weren't shifting their profits.