If you're concerned that you've somehow accidentally exposed something to the internet that you didn't explicitly intend to expose to the internet, you can just do a trivial port scan. You just run nmap, look at the output, and you're done in like 30 seconds.
What does this have to do with kubernetes? "Don't expose stuff to the internet that you don't intend for everyone across the planet to be able to access" applies exactly the same to literally everything you could run on your servers.
This isn't remotely "Kubernetes is uniquely scary and complicated"; this is basic fundamental network security, and if you're not already handling this, then you need to go brush up on your basic networking fundamentals, not blame it somehow on kubernetes.
Almost every network service I can think of defaults to accepting unauthenticated connections, or connections authenticated with some default credentials. This is the normal, expected, default situation with network services. If you make the decision to expose something to the entire world, in a professional context, it is your responsibility to know the specific reasons it is safe to do so.
Are you really trying to argue that "Some rando decided to bareback the entire global internet with no firewall, on a personal home server, and didn't bother to type 'kubernetes secure configuration' into google, therefore Kubernetes is super hard and complicated and dangerous"?
It's not like this is some obscure cryptic detail; it's explicitly called out in the documentation that any half-decent professional would read before deploying a production service: https://kubernetes.io/docs/tasks/administer-cluster/securing...
Controlling access to the Kubelet
Kubelets expose HTTPS endpoints which grant powerful control over
the node and containers. By default Kubelets allow unauthenticated
access to this API.
Production clusters should enable Kubelet authentication and authorization.
Consult the Kubelet authentication/authorization reference for more information.
Yes, untrained amateurs sometimes do dumb stuff. Sometimes companies leave their S3 buckets open to the world. Sometimes people expose mysql to the internet with credentials they ship to users. Sometimes people expose unauthenticated Redis to the internet. This does not mean that these technologies are somehow fundamentally too complicated for mere mortals, it just means that it's dangerous to ask amateurs to do something in a professional context.