I don't think so? It's mostly a result of the fact that (obviously) the best place to sell food is where there are people, which is also the best place to put a metro station. So on average the kebabs are pretty good and on average they're near a station. In Figure 9 one of the worst reviewed restaurants is over 3km from a metro.
You're likely seeing a pattern where there isn't one, which is normal for humans.
There's one obvious place to go around here for a good kebab, it's a few minutes walk to the station, but the way you can tell it's the best place for a kebab is how late it's open every night. Long after other kebab places are dark they're still doing enough business to justify remaining open.
The best place for pizza in my city is very close to a train station but that's a total accident, they park (it's a van, no really, best pizza in the city but they hated owning a restaurant so they put their oven in a van instead) in the car park of a railway station's pub about five minutes walk from me.