Just would like to share a good article. Take a look here https://drunkcoding.net/posts/az-00-pulumi-private-aks-environments/

Nice! Tho I've never understood why these guides seem to favor vnet sprawl - I much prefer a single underlying vnet instead of these micro-vnets per aks cluster. It doesn't make sense to me especially in Azure where peering traffic actually costs money

Understand, actually it is not much different from multi vnet as in the az-03 project is creating ask with a vnet. You can link an public ip directly to aks and no peering required. This article is more for enterprise with central firewall and outbound controlling not about the traffic costs