Because the assumption is as most often is the situation the US won't ask it will just do as it pleases. It may be due to pressure from states, citizens, lack o

Because the assumption is as most often is the situation the US won't ask it will just do as it pleases. It may be due to pressure from states, citizens, lack of water seen as a destabilizing threat, no time to debate or negotiate or the US would be impatient, or just arrogance. Because once water is sold as a commodity it can't be stopped. That's why trade agreements go out of their way to not even dare mention or very precisely say how sales of water isn't on the table. Lots of countries sell us food and we sells lots too. Take tomatoes for example Canada produces a crazy amount of them. Same for wheat millions of tons exported. See reason #2.