Because running red lights is dangerous and the governemnt could gain some funds by fining the idiots who do it!
How many cyclists have you seen run a red light? 80/90 per cent of the ones I have seen do it. If that was a motorist caught by police they would eb in serious trouble.
Cyclist should be fined for this as it is a dangerous practice. It may cut down on accidents and also create some revenue for the government. How about £100 a shot!