Draconian enforcement might be better in the long run, since the laws would get changed.
But many believe they're not. In my case, I believe most speed limits were set for a prior age, and modern cars can safely handle more than the obsolete speed limits now.
There are endless discussions here on speed limits, and they are mostly negative about their effects:
http://www.google.com/#q=speed+limits+site:news.ycombinator....
fleitz - "Interestingly, most accidents occur below the speed limit and increasing speed limits decrease accidents"
"in Montana after a Judge invalidated their speeding laws as unconstitutional the number of accidents dropped"
http://www.hwysafety.com/hwy_montana.htm
"Speed limits on roads are almost always political decisions, not engineering ones. How else do you explain the straight as an arrow, flat as a pane of glass, brand-spanking-new, 60mph limit roads crisscrossing the american midwest"
The best speed limits I've seen were on German highways - they were variable speed limits based on road conditions (that actually made sense !!! ).
And people are still breaking them.
Simply because a law is violated by the majority of the population doesn't ipso facto make it a bad law (although in some cases this is certainly true). For example, many people break speeding limits, but we also accept that in some cases speed limits are justified. It's a matter of degrees.
'Sexting' laws are similar to age of consent laws. For example, a 13 year old girl (or boy) sending indecent images of themselves to someone many years older than them is clearly a problem. Two 13 year olds sending indecent pictures to each other may be morally concerning to some, but it's not going to bother the law.