Trains with only SL/General coaches should be run as clones on routes where such overcrowding in trains is there.
However, recently, there was an incident in Patna Ranchi vande Bharat , where many people entered the coaches in name of being rail employees on election duty. They occupied seats of passengers with reservations and asked them to "ADJUST".....
I...
more... can recollect an incident from my childhood - In early 2003 , An old lady entered the lone 3AC Coach of the then Amritsar Jaipur Express (via firozpur) at Beas. She sat on our reserved side lower berth . She did not have a ticket of any class - when questioned - she told her son had asked her to just go and travel in AC coach. The TTE asked her to alight at the next stop , she refused and threatened to jump off the train . She also refused to move to the general coach of the train . She had some talk with the TTE near the coach vestibule. There was no RPF on the train and the TTE did not press her any further and quietly went away . She kept sitting here and there , on different seats in the coach - much to the dismay of the passengers . The coach attendant informed the next morning that she had deboarded at alwar .
This was the first incident of unauthorised boarding I had witnessed . So, this happens even in trains with sufficient sleeper and general coaches.
The issue of reduction of sleeper and general coaches , and lack of dedicated superfast trains/ clones with only sleeper and general coaches - is a serious issue that needs to be addressed ( Unfortunately Hon'ble rail minister had openly refused to acknowledge it) - but it's just "a part" of the problem.
People in some areas of the country have got habitual to committing offences like unauthorised boarding , with no one to stop them. And that is due to lack of vigilance staff / lack of will on their part to act - corruption is preferred over enforcement of regulations - ultimately encouraging such offences. Strict regulations and their enforcement is , thus, required.
So , a holistic redressal to this problem, taking all aspects into consideration , is need of the hour .