This is a logic gap. Buying things at a higher price ≠ paying a tax. You can not buy the steel Zhang can't refuse to pay the tariff, big difference.
Tarrifs are taxes. Tarrifs result in a higher price. By your logic Zhang can refuse to pay the tarrif by not making sales. Neither Zhang, nor the customer wanted the tarrif. Its imposed by a third party who leeches value as a tax.