I see that where I live.
I moved from a very affluent part of London to a very deprived area of the West Midlands. They are the polar opposite of each other.
In London, so many people deferred summer born children. My older two children were both November, so it wasn’t an issue for me, but I had lots of friends who had summer borns who all chose to hold them back, mostly due to concerns for the 11+ exams.
My 4 year old, born here is an end of August baby. All my friends back in London just expected me to hold her back a year. They were horrified when I said I wasn’t, even though they know her and knew she was already starting to read and write and was socially ready.
When I mentioned that to the school here, the head of KS1 laughed and said no one does it here, I don’t think most know what that is, they can’t wait to get the kids out of the house all day. It’s not a case of not paying nursery for another year, it’s a very deprived area, many parents aren’t in work and the children get free hours from 2 years old.
From what I’ve seen, it’s very much a class thing.