I'm agree with senoj, but do note that the average IQ is 100 and...

I'm agree with senoj, but do note that the average IQ is 100 and simplicity is a factor in the choice of many. Condoms, diaphragms, timing are all effective and easy methods for birth control yet how successful was/is the contraceptive pill.
There's many other example and behind most of them it boils down to marketing. It could be argued and was that GSK purposefully did not market Relenza and certainly did not give their best effort.
Whether it was the pill vs inhaler, Rumsfeld vs Relenza, or Roche marketing against GSK's devious dealings, doesn't alter the picture in front of us.

Due to Roche's success with Tamiflu resistance is becoming prevalent.
Due to the systemic nature of Tamiflu, it is polluting Japanese water ways and getting into bird life, more resistance this way comes
Due to being forced to produce more Relenza, GSK are upping their production.

Could GSK be doing more? Yes, probably they could, but even their 190M increase is enough to justify the current SP.