Financially, I know, it's not efficient. It's not for most people. Neil DeGrasse Tyson once said that, for example, Bill Gates earns so much that it would only be worth his while to pick up money on the ground if that money totaled tens of thousands of dollars. I'll never earn what Bill Gates earns (unless my life has some MASSIVE plot twist), but picking up dropped pennies is not going to fund my retirement. But I'm glad to do it.
Environmentally, picking up coins is a good idea, especially pennies. In 1982, the U.S. Mint changed the formula for a penny from about 95% copper and 5% zinc to the other way around, almost no copper and mostly zinc. If a person, or an animal (like a dog or a cat) swallows a penny, the zinc would react to stomach linings much more than copper would. I don't like to imagine people or animals getting sick from swallowing a penny.
It may not be likely, pennies getting swallowed, but by picking them up I make it less likely. I can feel good about that.
As for pennies in general, maybe eventually we'll simply stop making them. A few other countries have...
This entry is brought to you by the 14 pennies I found during today's walk.