Besides the obvious punitive punishment to actual offenders, LTA needs to start looking into how these clowns even managed to game the system to begin with.
There are so many teething issues with our transport now. PMAs, PMDs, drivers with licences who drive like they barely cleared the TP test, drivers without licences who are going around killing their passengers.
There's no point addressing the symptoms by only jailing the small fry. That's like catching drug runners without going for the syndicate bosses.
Just make it a clear cut case of vehicles used for such purposes = confiscation with no return unless the vehicle owner can prove beyond doubt that he wasn't aware.
You'll see the number of cases absolutely plummet because the cons outweigh the benefits one hundredfold.