Based entirely on the premise "someone else will pay"
Similar views have been put forward since the start of railway preservation. They were hopelessly romantic then as they remain. A fair deal of money was lost in finding out just why the railways closed in the first place which was not due to any wickedness on the part of "them".
Are there any instances where a heritage line could work operate a commuter service without needing any external funding? Maybe selling season tickets? Or are they too unreliable for those who need to get from A to B?