There is no deterrent these days, people commit crime because they can get away with it.
Bullies don't target people they believe are stronger than they are.
I take my daughters dog to the park, there are signs saying all dogs must be kept on a lead, yet some dog owners let their dogs of the lead as soon as they enter the park.
Anyone who points out to these dog owners that their dogs should be on a lead usually get a mouthful of abuse.
Its the same reason people hunt Foxes, they do it because they can, they know there is feck all the Fox can do about it.
Another example of this trait in human beings was one day i was talking to a mate who runs a kickboxing club, he had just come out of the club and we met in a carpark outside an Iceland supermarket.
We chatted while he waited for his wife to collect him in the car.
His wife arrived in the car, she was driving very slowly while looking around for my mate, one guy driving behind wound down his window and started effing and blinding at her, telling her to get out of the way.
When my mate saw this he walked over to the guy and said "Thats my wife you are shouting at" the bloke's demeanor changed immediately, his face went white and looked quite frightened, he knew instinctively that he could be in trouble, anyway my mate invited the bloke to shout at him in the same manner he had shouted at his wife.
The bloke in car declined the invitation and then reversed his car and left the car park.
That in a nutshell sums up how humans behave.