I also think it is wrong to equate a lamp with a knife. For a lamp as I explained, you have no reason to be touching it often once it is in place, let alone hold onto it for more than a second for the light switch, indeed, maybe it was a light switch in the wall so you do not even have to touch the lamp
With a knife, while eating, you are putting pressure on the knife to cut for 30 seconds or so at a time. It is much more likely to leave DNA when you are using the device in that way.
How is DNA on a lamp different from DNA on a knife ... other than the fact that is was not sweat on the knife and it was between the handle and the blade?
Why wouldn't Knox turn the light on each day? Did she do everything in the dark?
I shouldn't be surprised that there are now excuses for the alleged absence of Knox's DNA on her lamp, but I am. Of course there's no DNA belonging to Knox on her own lamp, even though it was the only light source in her bedroom. This is normal. The absence of her DNA in Meredith's bedroom is also normal, or not normal, or it means that she had never entered the bedroom, but her lamp was there, but she didn't put it there because she had never touched her lamp and even if she did touch her lamp, it was only for a fleeting second and if someone touches something for a fleeting second, no DNA is transferred.