[stale2002]

Correct. And?

Yes roads have benefits. They also have costs.

The benefits are greater than the costs, but we should be aware that the costs still exist.

[mattkrause]

If the benefits exceed the costs, it’s hardly fair to argue that the program slows economic activity.

[stale2002]

Slowing economic activity IS the cost.

And the benefits outweigh the cost.

[mattkrause]

Yes. And when a program's benefits outweigh its costs, it seems weird to say that the program is a damper on economic activity.

In other words, if Option A is "get zero dollars", and Option B is "spend $1 to get $2", it is unfair to complain about B's "cost" (spending $1) in isolation.