Note: Azure does not charge a master/cluster management fee (bias disclosure I work for Microsoft)
Replies on another thread by alleged Google employees appear to indicate they are learning on the fly that doing support matters and costs money.
There are a lot of comments from people wanting free things. You may get those things for a while but it won't last. Free only works for so long in anything no matter how hard that is for some people to figure out across all aspects of life.
>As a free service, AKS does not offer a financially-backed service level agreement. We will strive to attain at least 99.5% availability for the Kubernetes API server. The availability of the agent nodes in your cluster is covered by the Virtual Machines SLA. Please see the Virtual Machines SLA for more details.
google didn't have one either, so they added it + a price for said SLA.