This is not exactly racism. It is a different kind of bias based on the same physical feature but you will see it between members of the same family. So for e.g. if there are two sisters in a family and one has darker skin, she is very often subject to discrimination. So also with brothers though to a lesser degree (so this is not entirely gender based).
In short this is bias, and it is horrible, but it is not racism. Interestingly this bias does automatically RESULT in racism, so you would typically see people of African origins depicted as goons in older Hindi movies. This has changed slowly. I am quite sure the rising popularity of rap and Hollywood has contributed to this change.
I don't mind spending an hour or a day understanding why they think the way they do. What I would mind is spending years at it, coupled with selling them something they think they need when what they really need is a change of mind.