Working out how the tavern functions in Manor Lords is an important step in caring for your families. Tavern supply is one of the listed amenities alongside church access and water supply, so it's a necessary provision if you want to upgrade your burgage plots to level three. This will let you collect more regional wealth from them per month, but more importantly, is a condition for becoming a large town.
That said, this isn't your bog standard city builder where you can just build a thing and it'll function perfectly.