Because the value of items when the statue was enacted has not kept pace with current valuation. They did not steal a car, nor electronics. While I am not defending them stealing Walmart property, their stunt was nothing more than something kids did years ago. The point I am making is that they are incredibly stupid but hardly felonious. If the only reaction to any crime, no matter the severity, is to charge someone with a felony, we will all be criminals in short order.
Perhaps the state needs to enact a new misdemeanor offense, something on the order of “borrowing without permission,” which would cover situations where the property is recovered, intact, in short order.