The best analogy I can think of is asking a non passport holding American why don't they learn Japanese to attract business from one of the largest economies in the world.
Learning a new language as an adult is incredibly difficult. I have learned Spanish to a basic conversational level and it has been a massive struggle for me.
My Swiss and German friends seem to pick up new languages super easily though. Likely this is because they learned a second, third, or even fourth language as children.
So, not impossible but it is good to acknowledged that this isn’t an easy thing to do and likely would be a generational shift kind of thing.
Most of them can read and write it passably, but can't speak it confidently and as per culture, if they can't do it perfectly they don't want to do it at all.
I'm not sure they need that kind of business.