If the software screws up and the item count is incorrect in the favor of the customer (ie, charged for 3 rather than 4+ widgets), who eats the cost? Have you

If the software screws up and the item count is incorrect in the favor of the customer (ie, charged for 3 rather than 4+ widgets), who eats the cost? Have you hired sleight of hand artists to field test the machines? I’d be very impressed if a determined actor could not fool a set of overhead cameras.