HI Adam,
Totally agree with the comments that @joeyk made above - we are working to address these issues but we have had very little interest from the community in improving the developer documentation. We absolutely would value some help in this.
We have an Education Team which is responsible for this and who work closely with the Product Team. Join us on Slack (https://mautic.org/slack for an invite) and join #t-education and #t-product respectively.
We are also in the slightly longer term looking to move to API Platform based architecture, which will have quite an impact on our developer docs in a practical sense.
If you’d like to contribute to improving the Developer Docs in the meantime (including adding code samples!), you can make a PR at github.com/mautic/developer-documentation - this is where all of the dev docs are built from.