How it works
Maps tell you where pubs are. Drinks apps tell you what strangers thought of them. Neither answers the only question you actually have.
For drinkers
Where the data comes from
Most pubs put their drinks somewhere: their own site, a PDF, a booking page. None of it is searchable by product and price. We read it, attribute it, and label it as what it is: a published menu that may be out of date.
A photo of your drink, taken at the bar, with the coordinates to prove you were there. That is what turns a price somebody typed into a price somebody witnessed. Catching a wrong one is worth the most points in the system.
Once a venue claims its listing it can connect its POS, and its prices become live: read straight from the system that charges them.