Corstorphine catchment has recently changed, or more accurately is in the process of changing. Maybury primary has taken the remaining chunk of it's historical remote catchment. Even with that change it's furthest point is about 1.2 miles away in East Craigs Rigg.
But Maybury primary school isn't yet open and even when it opens later this year it will only have primary 1 pupils. So I think we need to consider Maybury as part of the Corstorphine catchment a while longer. This means the furthest houses are Nether Lennie and Lennymuir which are both over 2.5 miles away. I think this makes it the "urban" primary with the most remote housing.
I can understand why some in the catchment might feel they have no choice but to drive, however assuming an even spread of kids across the houses in the catchment I doubt there are 200 kids at the school who live more than 10 minutes walk from the school.