As a former owner of a service establishment - I know the challenge of adopting new technology even when it seems to have benefits. The more concrete you can make the benefit - and the more focused you can make the impact (from a time standpoint particularly) the better. Try to demonstrate the value of this in as short a period of time as possible - if it takes months to show a return - its probably too long.

You can kill two birds with one stone by driving adoption around a specific, exclusive event. This gives you the hook you need for the bar through promoting the event to your population (and focuses impact into a short time window) - and you can motivate/attract the population by offering a discount on the cover in return for utilizing the app - or by offering free entry for any user who invites 3 or more friends who attend. You can even make that a long term tenet of the service - because it will serve as a dual incentive (free admission for the users - higher attendance for the bars).

Once you've executed this with the first location - it becomes a demonstrable case study for the other bars. Like anything in syndication - once your competitors are using it - you have to adopt it or risk falling behind.

Happy to discuss further.