Probably results in less paperwork and easy conviction , rather than driver error or other more likely reasons which require more investigation.
All I can say is that during the time I've been driving / riding , which is 25 years now , I can say that I see more potential for accidents resulting from driver incompetence , inattention , distraction or outright stupidity than speed itself. If drongo drivers were prosecuted for not indicating before a lane change , inability to negotiate a roundabout or junction , tailgating , driving too slowly in inappropriate circumstances , lack of observation etc the roads would be much safer. Of course that requires more work and less speed tax revenue for the Government.