For that matter, nor do the people. People are happy to fake wearing a seatbelt here, so cares about airbags? People got aware and started asking about immobiliser, and Indus had to respond. If customers at showroom start asking and making their decision about airbags, the manufacturers will respond.
That, however, is unlikely to happen.
And frankly speaking, which someone else also pointed out, these kinds of things will have to be enforced by the govt. Even in developed countries, they had to be enforced by implementing crash test standards and giving out ratings.
Moreover, if such a thing is to be mandated, it will have to combine with insurance too. Imagine bumping into someone (or someone bumping into you)...what is now settled with a few thousand rupees (and a verbal/fist fight) will cost hundreds of thousands of rupees.
Who can afford that?
I know people (in rural KP) who have bought JDM cars and went to mechanics to get the airbag disabled.