Footfall is not time available to rent
A customer who is in and out without a pause has no moment to start a portable charger rental. In the quick-stop situation, the customer is already counting the queue as time spent off the road. Starting an app-based rental competes with buying the drink, and taking the bank back to the vehicle leaves another errand before departure. That is a timing problem, not a signage problem.
A station visible from the coffee island does not by itself change that visit. Nor does a busy register prove that customers want to carry rented equipment. The owner should separate people waiting to pay from people choosing to remain on site; only the latter pattern offers a plausible reason to charge and then return before leaving.
