I think you'll find that with every school there are differences like that.
My DD thinks that money grows on trees & that is nothing to do where we live or where her friends live. Kids don't really have that true concept until much older.
I joined a play group at school & meet like minded Mum's through there. You might find those groups that stick together are all on the PTA or what ever your school calls it.
I wouldn't say I've gained friendships with the Mums at school, although I've become friendly/acquainted with the Mums in her class, this is more to do with when she is invited to parties.
I'm also not bothered, if they're not warm and welcoming then I'm not interested in being their friend. Just smile & say hello as you walk past