I reckon people will take an interest in promoting something they can recognise and know as their own. In a brew pub and restaurant I ran in Oz we would explain to the customers on a daily basis what the beers tasted like and what the styles were. Each new staff member whether they were floor or bar, would have to be able to explain to customers what the beer tasted like.
The fact that the mangers and supervisors had passion and knowledge about the product meant that passion and knowledge would filter down to the rest of the staff. Instilling this sort of level of service has to be driven from the top down, otherwise it wont work.
Also, people in charge need to make it clear to bar staff that it is part of their job to understand about the beers. It is infrequent that someone in a wine bar has no knowledge of wine. Similarly in a brew/gastro pub, if the staff member is uninterested in the beers/food, then maybe they are just not the right fit for the place.