Sometimes they do, depends on what the item is and what the support is.
What you seem to be arguing (and please correct me if I am wrong)is that we have to artificially support producers in order to prevent there being massive layoffs. Then we have to artificially support consumers, in order to prevent starvation. Yet if we do this, (and we total up all the costs involved) we end up paying far more for food than we would have if we would have just left the whole system alone. I know that tough decisions are tough (duh). But the government NEVER makes a given situation better, over the long run.