Thats because you are comparing a 2010 MBA to a 2007/2008 netbook.
Compare it to a 2010 netbook like a Dell/Alienware M11x.
Except that's called a "CULV-laptop", not a netbook. (and BTW it weighs double than the MBA, and has a worse display quality, half the contrast, half the brightness, see Anandtech)
Likewise, the MBA is a CULV-laptop. No matter if the screen is 7", 11" or 13".
Also, sub-notebooks and thin&lights existed well before netbooks. Should we call them "netbooks" too because they squak like a duck?
On average a netbook is
roughly defined like this (and that's been quite CONSISTENT in the last 3 years of the netbook era):
- cheap and bad LCD panel
- an ATOM or ATOM-like CPU (not a full blown C2D, even if LV/ULV)
- GPU not good for 3D gaming with current gen games
- 1-2gb of ram (there may be exceptions)
- cheap squeaky build quality
- non fullsize keyboard (again, there may be exceptions, I said "roughly", but that's not about 2008 vs 2010 as you were implying, the AVERAGE, the GROSS of the netbook sales is like I'm describing, both now and in 2008)
- a 10 years old operative system (XP) or a castrated cheap version of the current operative system (called Win7 STARTER EDITION, not even enabled to change wallpapers!!!! 32bit only!), whereas the Apple CULV-laptop comes with the FULLY FEATURED version of the current version of OSX, in windowsland we could call it
OSX Ultimate x64 (mind you, Win7 Ultimate costs like 399$ alone, like a whole netbook).
Hence, the Macbook Air is not a netbook.