Different context which doesn't apply to my initial post, and worded in a harsh manner to attempt to demonize my idea without presenting an argument against its merits (i.e. "around your neck"), but I'll bite.
Stepping on an individual's property doesn't endanger others' lives needlessly. It's pretty easy to call the police and have a trespasser removed/arrested. Plus, in some states, you can shoot and kill trespassers so long as you've given them fair warning, and can legally carry a firearm. People also have attack dogs, surveillance systems, etc...
You can't shoot and kill someone who's speeding endangering your life. If you call the police about a speeder, they'll usually look for them if they're not too busy. But police departments would quickly be overwhelmed if they had to police "every" speeder on the road. There's simply not enough police. Also, you're defenseless while being in the presence of their illegal driving behavior.
Trespassing, on the other hand, is a rare occurrence. Penalties tend to be harsher than speeding (jail time rather than a fine). It must be much easier to speed than trespass since I don't know anyone I've met in the last year who hasn't sped, yet I can't pick a single trespasser out of any of them. I'd imagine this is the same for most people.
People have little incentive to trespass too. Why do it? To steal something? Murder? Most people don't need to steal things or kill others.
Speeding, on the other hand, has a number of incentives tied to it which provide immediate benefit without significant perceived risk (tickets are rare - habitual speeders may only receive a couple a year | accidents are even rarer). For one, it might save you time^. It also makes people feel good (release of aggression, showing off, feeling of freedom, etc...).
My initial idea isn't one of punishment, but one which increases safety. What's the goal of driving? Going from A to B in a safe, efficient manner. Why wouldn't you want it to be safer, within reason? So you can cut 4 minutes off your 60 minutes of travel time?
^This isn't always the case. Roadways are much like assembly lines. Their slowest points set the pace of everything on the line. Speeders mostly zip from one bottleneck to the next, never really decreasing their net travel time. Time yourself driving the speed limit to work and back one day, and time yourself speeding the next. How much time did you save? A minute or two? None at all?
NOTE: Most vehicles already have governors which limit their top speeds, though aren't used in the manner which I suggest: http://en.wikipedia.org/wiki/Governor_(device)