I think this is a systems design problem in the category of failing to include a functional system/business method for reversing an invalid record, i.e., an incorrect record of non-payment.<p>SF Muni also has a phone payment app, but even most people who don’t use it do not have a physical receipt. If for any reason the Muni inspector can’t scan your BART/Clippper card there needs to be a reasonable way to use other proof of payment to correct an erroneous record of non-payment. This is the same situation as if one's phone died after using Apple pay to get on the bus.<p>The failure to create system methods/business methods that allow for reasonable correction of erroneous records is unethical, but unfortunately common. Think of: cleaning up after “identity theft”, or trying to get removed from the the no-fly list. I privately think of this as a 27b/6 error.