It’s probably been zoned that way for a long time.
Probably, gas stations are low enough in profit they’re usually capitalizing on existing zoning rather than working the system to change it. If the name really is Bill Pump N Snack though it’ll probably die fast. At least here unaffiliated gas stations rarely live more than a year. Of course then you have a derelict former gas station in the neighborhood inviting vandalism and loiterers. Not a lot of happy endings in this scenario.