Imagine a world where ubiquitous automated cameras sent you a ticket every time you jaywalked, or if your car automatically reported you every time you exceeded the speed limit.I'm probably being naive, but I think having rules that are universally enforced would be much better than our current approach of selective enforcement. I'd expect that as soon as those with power to change the law are negatively affected by poorly written laws, those laws would soon be changed.
Should jaywalking itself always be illegal? No, it should depend on whether there is an actual danger and the degree to which it impedes traffic. A more sane law would differentiate between calmly crossing at midnight on an empty street and causing an accident by darting into busy traffic.
Should it be illegal to exceed the posted speed limit? I think so, otherwise why not just have "advisory speeds"? Rather than making it illegal to exceed a speed that drivers are expected to exceed and then enforcing selectively, a firmly enforced limit seems much saner. If the goal is fuel efficiency, then legislate that directly. If the goal is safety, then "reasonable and prudent" seems sufficient.
like stealing a loaf of bread to feed your family
I think this is better dealt with at the penalty phase than by selective prosecution. I feel the owner of the lost loaf of bread should have the right to prosecute or not prosecute entirely at their discretion, but once the police are involved I think they should be required enforce the law and leave the discretion to the judge. It it would seem terribly unfair to the property owner for the police on the scene to summarily decide that the theft was justified and the shop owner must absorb the loss.