There may be several reasons why foreigners don't like to drink green tea and prefer black tea:

Tea originated in China, because of logistics reasons, tea from China to Europe is almost half a year, there are good green tea should be spoiled. They can't appreciate the fresh flavor of green tea, and they don't like to drink green tea.

Black tea is easier to store than green tea, and does not deteriorate as quickly at room temperature. Good black tea is a bit sweet and floral. Foreigners like it better.

Foreigners like to add some messy things to their tea, just as Chinese jasmine tea is especially popular abroad. Foreigners drink tea like to add sugar, ah milk ah, mint ah, lemon ah, vanilla and so on. That is the so-called drink mixing. And black tea and these things can better dissolve together, and green tea in favor of drinking, not suitable for drinking so do not like to drink green tea.