I've seen comparisons of criminal penalties in the past that make this same point. For instance, I think abusing animals in certain ways gets you a worse punishment than if you abused a child the same way. No doubt the laws are riddled with unfairness like that. It might be an interesting project to rank crimes by penalty to see which are the most and least punished.
This article is about the use of an automated system to detect a particular violation of the law. It makes a point that may be relevant here:
Wholesale surveillance calls for something else: lessening of criminal penalties. The reason criminal punishments are severe is to create a deterrent because it is hard to catch wrongdoers. As they become easier to catch, a realignment is necessary.Is shoplifting punished lighter because it's easier to catch shoplifters than downloaders? I doubt that's the reason. Still, I doubt that relating penalties to each other is as simple as it looks.