यमला-पगला-ट्रेन का-दिवाना - कार्तिक

I don't think there's much demand for sleeper buses. Because unlike trains buses aren't spacious. And people prefer to sit alongside a stranger, rather than sleeping. Then there's hygiene. So, instead of handling situations like this, they're running what's easily acceptable.

Added bonus, pocket friendly to passangers, more passangers means more revenue. And looking at the almost fully occupied buses, it's not even bothering them. Delhi-Manali sector requires long travel times, but buses either HRTC Himsuta or from private operators are all of sitting type. Same for Delhi-Jaipur or Agra-Rishikesh routes. Because...
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that's what people prefer.

For sleepers, people prefer trains. I haven't seen a single UP Roadways with Sleeper configuration, even though I've read that they operate a few. Even private operators are mostly running on the routes where trains aren't in higher frequencies.