Business owners usually provide it on their door. I added opening hours to many places, and importantly I didn't have to add opening hours to many other because they already had them.

> For real time bus/rail status you need integrations to countless public transit systems.

For public transportation, I personally usually need to buy a ticket, which Google Maps doesn't provide. So I use the public transportation app of the country in question. For countries where public transportation are public, which usually implies an app, of course. Countries that have broken public transportation won't work the same, but anyway the public transportation is broken there :-).