I'm sorry that you're frustrated. Maybe the following will help?
There is such a flag for your use case[1]. Start the node in the Docker container with
discovery.type: single-node
This allows the node to bind HTTP and transport protocols to non-localhost interfaces and not enforce the bootstrap checks[2][3]. The node can not form a cluster with another node, but that's okay for development use cases. It's design was intended to address the Docker development use case.
I hope that helps!
Disclaimer: I work at Elastic; I welcome any and all feedback