It seems a common phenomenon around the world that, because price instability for food leads to social instability, governments end up with elaborate systems of direct and indirect price control. In this case, farmers being paid not to grow rice.
Not that rice would do anything so nefarious, but more to point out that large scale purchase and storage is not a trivial task. I can imagine the scenario where some bureaucrats ran the numbers and concluded that it is cheaper to just give the money to farmers instead of running the purchase/storage scheme.
The problem is, the other option here, the Futures Markets has Goldman-Sachs using their vast cash reserves to buy in when it suits them so as to make money on the people's daily bread.
Like many other things, "It's better to have it and not need it, than need it, and not have it."