You almost never have to walk to the courtesy counter; you can fill it out while standing at the checkout. But people typically don't know this, in my experience, and the cashier is unlikely to enlighten them, since then he'll have to wait for them to fill it out while there are people in line, etc.

Things like this are important to know, and if you don't already just know, you have to ask about them constantly. If you don't know that, though, and you're poor, it feels as though you're asking for handouts or special help whenever you aggressively inquire about this sort of thing.