The reason is the same reason why bullies go after vulnerable and/or isolated kids. The type of person who has a car and has the money and means to illegally modify it is also the type of person who would give the police absolute hell if they so much as dared to look at them the wrong way. A person jumping a small toll is someone who is poor and will never attract the sympathies of any judge who will treat them very harshly.
The same thing in Canada. Despite the reputation of Canadians being polite wusses by Americans the Canadian legal system is much harsher than the American system.