I'm not sure how far councils can go, legally, but I presume they're entitled to tow the offending car away and charge the owner the costs of recovery + storage + parking fine? It doesn't need to hurt the offenders financially, the council just has to be able to deal with the problem without making a loss. And the inconvenience is far greater than parking legally in the first place so if the council can remove more than a fraction of the offending cars, it'll no longer be worth parking so brazenly illegally.
What might become more worthwhile is hiring a chauffeur, who could then just sit there causing the obstruction.. are police able to arrest you for waiting on a red route?