Why is there such a delay in completing education in Bangladesh compared to India?

During my recent visit to Bangladesh, I found out that many guys there are completing their degrees or bachelor's at 26, and some are even finishing engineering at 28. I also met a few who were preparing for degree admissions at 21.

I’m from Kerala, India, and in my state, most people finish graduation by 21. Why is there such a delay in Bangladesh? Additionally, many people there seem to be financially dependent even at 28. What could be the reason behind this?