This appears to be a judgment call JC, many corner stations were constructed with minimal visitor parking.
When service bays are converted (altered) to min-marts they attract pedestrians without cars and visitor parking is required.
Depending on where the existing building and pumps are placed there are limited areas to locate parking so the exception for using the drive aisle was created. At issue is corner locations where you may enter from either side. The choice of which one should be the operators, yes, closest to accessible entrance and yes to use a drive aisle which may are may or not require traveling behind parked cars just like at a big box site.
Yes, if designed new a separate and independent POT could be provided but if part of a barrier removal project only the exception should apply, no?