I'm surprised that's your experience to be fair. Mid sized cities like Columbus or St. Louis's downtown effectively shuts down at 5pm in my experience. All those tall buildings are offices, most of the restaurants around them serve business people and don't offer dinner service and close after the workday. Night life is in other neighborhoods adjacent, but not in downtown.
St Louis and Columbus are much bigger than the towns I'm thinking of. The two towns are basically suburbs with a downtown area. I was able to bike to both of them from my house. In my favorite of the two there were two restaurants that offered dinner service and were owned by locals. Everything else was chain restaurants and they all offered dinner and late night/bar services.
Yeah if there isn't a ton of office space downtowns seem a lot more lively, since businesses stay open outside of 9-5 and people might actually live closer by. Even lower manhattan is considered a dead area after hours due to all the offices and not a lot of other businesses and housing to draw demand outside of 9-5 m-f.
A lot of core downtowns (whether financial district or something more diverse) were pretty dead pre-pandemic after hours even if nearby areas of the city were pretty lively.
