Why Afghanistan never came under British rule?

India-Pakistan territories were under British rule in the 1800s, however Afghanistan was always independent. Actually not, Afghanistan came under British influence partially but soon was made independent. This wikipedia entry will explain it all.

There were a total of 3 wars fought between the Afghans and the British. The first 2 were aimed at preventing Russian influence in the region, however they ended in disaster for the British. They sent so many troops and very few came back. In the end they could just control the country from outside, but that control was quite weak and soon Afghanistan was free from all British influence after the 3rd war. If Indians had so much resistance, we would have been free long before 1947, however Indians aren't that vicious :-)

It will therefore take an Afghani who knows his people properly to rule the country. I hope Hamid Karzai has the necessary potential for the job.