Not sure about the colonial mindset or the caste practices of centuries but Indian culture is extremely hierarchial in almost all facets of life. Elders, seniors, higher officials, etc all expect to be respected even if it is just one year difference, etc.

One of the ways to show respect it to not use names and call as sir,madam, teacher, officer or at best elder brothers/sisters for college seniors. All this works well in the regional languages of India but sounds weird in English.

Directly calling names of elders is still seen as bad and if needed would use their name appended with sir madam uncle aunt etc.

This is less practiced in IT field in my experience. After years of schooling and college calling my teachers sir and maam it was hard to shake off the habit. A few of my managers had to remind me a bunch of times to call them by their name and not as sir / maam in the beginning. Even then I avoidedcallintg out their names and just started speaking to get their attention. Now I almost call everyone by name by default in office setting. It is still fun when freshers join and are asked to use names of 15+ year elders and them wondering if we are joking.