Better information does not necessarily allow faster reaction. It could lead to information overload. In general, I think the problem of how to improve buyer reaction times in a market is going to be a lot harder than "give them more/better information" (although simply providing more/better information may indeed be the solution for some markets).

Also, that mobile app (or several) exists. But they rely on users reporting the data, so there are significant network effects -- the more people use it, the more timely and useful the data becomes.