Well, looking at it this way, they are both offences that place other people in serious danger and result in a genuine risk of injury and/or death. So you could argue they really are on the same level of seriousness.
Speeding in the pitlane results in a fine pre-race or usually a drive through mid-race. Your ‘taking out another driver’ could range from a slight brushing of endplate against rear wheel to full on t-boning somebody out of the race and the penalties can be varied from nothing at all through grid penalties to a full on race ban or multiple race ban.
The reason many drivers are given drive through penalties (which is what I assume you are referring to) is so that the offending driver receives some sort of race disadvantage/penalty without the need for black flagging them.
What would you prefer, an instant black flag for every incident??
No, for example Belgium 2010, Vettel got a Drive through for t-boning Button and ending his race, yet the same penalty would be applied for speeding in the pitlane or cutting a corner. Its just a thought I had
Speeding in the pit lane gives one a clear advantage over his competitors, a crash usually doesn’t. That’s why drivers shouldn’t be punished for ‘causing avoidable collisions’ at all, unless they collide deliberately.