"Why is this privatised? Too easy to abuse."
Because the government never participates in abuse?
Because the government never participates in abuse?
I think government malaise and/or regulation vs privatisation is a real balancing act. Companies motivated by profit and using some of that to lobby for less regulation or whatever can lead to real trouble.
A privatised prison system lobbying for harsher sentences, or against legalisation of marijuana can get ugly fast. In the case of speeding cameras, deterrence as an ideal works very much against the profit motives of privatised providers.