Bro, both 0w-20 and 5w-30 are recommended oil grades for brand new Civic, BRV and City models (although I am a bit skeptical for 0w-20 in City). You can check Honda Atlas website for confirmation and further details.
Other than OEM recommendations; the reasons are also from $$$ / business point of view. Since 0w-20 is expensive in comparison to 5w-30, and in costly oils dealerships have more profit margins, that is also one of the reasons.
Irrespective of 0w-20 or 5w-30, your engine is safe in both cases and both re OEM recommended oil grades. Trust me!