Weather apps don’t do real time analytics, but show you the forecast some nearby weather station has calculated. Whether that’s based on current data or a couple hours ago depends on the exact provider they use. And hardly anyone of those are done by actual humans, it’s aggregated statistics.
If you look at precipitation maps, you are doing that forecast by yourself based on cloud movements and local knowledge, something no machine-generated forecast can do as good.
Plus, there’s usually one weather station covering a large area, so hyperaccurate predictions would have to be made just for you - which simply costs to much.