That's what I said these are single travelers for they have upgraded to 3AC just to avoid the hell that SL class has become in last few years but others too exist who will find it difficult to afford 3A or 3E fares.
But seeing here the train running full we can say that demand exists for AC travel even on this route and those who could not have afforded AC must have used alternatives like connecting trains from Mumbai.
Also IR does have an argument in their favor that they are...
more... running in losses so the solution would be to run these rakes standardized as it is if they are running full and as some RF had suggested few days back here on IRI separate trains should be run on routes like this having only GS and SL coaches on the lines of Antyodaya. A win win situation for railways and both AC and Non AC passengers.