Comment by ndsipa_pomu

No, that's been disproved. Most people don't consider that they'll be caught and so the penalty isn't relevant to their thought process. What does deter is a high likelihood of being caught - so a small fine will be more effective if the detection/enforcement is sufficient. Also, it's often not feasible to tie up the courts and jails with minor offenders (e.g. speeding, using a bus lane etc).