If you see a penny, do you stop to pick it up, as the old saying goes? Hardly seems worth the trouble. Bending over and obstructing pedestrians only for the sake of a piece of shrapnel that has no real worth. Of course nobody wants to be a litterbug with their small change and leave it lying around but beyond that impulse what is there? The motivation not to pick it up probably stems from the same place as saying "keep the change" when you buy an item for £9.99 and get a single penny back.
There was a teacher at my high school called Mr. Bell. He was pretty old and near retirement and had some old-fashioned habits that kids loved to make fun of. One of these was that he would always pick up coins he found lying in the street.
Walking home after school, if anyone spotted him on his way home, they would throw coins in his path, just to watch him stoop to pick them up. The coins that were thrown were always 1p, never more than 2p, as the humour seemed to reside in how laughably worthless his efforts were.
I like to think he kept one of those giant Bell's Whisky bottles in his house, half full of pennies, on its way to being full of whisky once more. He was from a generation that remembered the value a penny held, both real and symbolic.