Then why do none of my users complain about it? Because nobody notices the difference. The only difference they notice is between their old notebook and the new one. Which is obvious because the new machine has more mem, a faster disk, faster cpu and faster gpu.Just go to notebook check and notice the difference in framerates between the k1000M and GT650M in Solidworks for example (which is the same card architecturally speaking).....its like 400% difference.
Also, what you are talking about is performance on paper for 1 specific component. In reality most will not notice those differences because it is the entire machine that counts, not just the gpu. It is a matter of cpu, mem, gpu, disk and software. The machine will only be as fast as the slowest component. You can have a very fast card but if the cpu and mem aren't up to par you'll have crappy performance.
Performance means a well balanced machine in terms of hardware AND software. Performance does not mean a fast component. It helps if you actually know how a computer works.
They make a (noticeable) difference for the software that they are optimised for which isn't all that many. They certainly do not make a "HUUUUUUGGGGEEE". It is not like light and day.those drivers make a HUUUUUUGGGGEEE difference.....and cannot be had on "any other card"