Actually motorcycle are popular in India. Most people use motorcycles in India. It wosen the traffic as bikes can cut between cars.
Motorcycle aren't as safe as cars.
Given average speeds in India this isn't as much of a problem in practice as you might think.
My impression of India isn't a population that prioritizes safety. Just look up footage of trains in India, there are as many people clinging from the outside as there are inside.
I've travelled on a few different trains in India. More than a few actually, though not close to a hundred. Without seeing a single person clinging to the outside.
I've seen those in films and on photos, yes, just not in person. So maybe it's not that common, really? Except when a million people need to flee from the latest flood in Bihar.