Very true, you need absolutely no flight planning knowledge to drive a 737 / A320 up and down the east coast. Taken to absurdity, all you need to know is how to start the engines, read a checklist and turn the autopilot on. Some rudimentary taxiing and flying skills might also be convenient.
There may be a case for CASA to issue “Restricted” ATPLs which are only valid while the holder is in the employ of specific airlines who meet some operational criteria. I wouldn’t doubt that one could train a 50 hour PPL holder to operate a simulator A320 up and down the coast in less than 200 hours. Then one year RHS to get the hang of line operations and then a command.
And this is why airline managers and aircraft manufacturers are working away at designing uncrewed or, at the very least, minimally crewed aircraft. The less you need to know to perform a task, the easier it is to automate.