@jonagpa,
jonagpa wrote:
Ive thought about this and I think its possible it has origins in this expression, but I think its still its own. I guess a better question is, how would you say it:
level plain society
level plane society
You mean "how would you write it", since "plain" and "plane" sound identical, and you would say them the same. Maybe it's a local English expression in your country, India maybe? Or you misheard it. Certainly not used in mainstream English. If you insist, "plain" is geographic, and "plane" is geometric.