To keep depleted batteries from polluting the environment, the government of Ulm is discussing a mandate that would require residents to dispose of them through a special pickup service. To offset the costs of maintaining such a service, Ulm expects to charge a fee, which would be collected when batteries are discarded. Collecting the fee at the time of sale would be more effective, however, because residents are more likely to make use of a service if they see themselves as already having paid for it.
Which of the following, if true, most seriously weakens the argument?