If you reduce the subsidy for corn, there will be less corn grown.
Suppose the subsidy costs $20bn (the amount of the proposed bailout), and sure the subsidy brings money into the USPS to sustain its trade.
This is self-evident, I acknowledge it. The postal service does its thing, the mail truck comes, puts the circular in the mailbox, keeps an eye out for mean dogs, gives treats to the nice ones and he finishes the route and goes home.
All this is that which is seen.
However, this is confined to that which is seen; it takes no account of that which is not seen.
It is not seen that the taxpayers have spent the subsidy on one thing, the taxpayers cannot spend the subsidy on another.
It is not seen that if they had not had an inefficient postal service to subsidize, they would, perhaps, have done any number of things.