Yes, apple has gone on record they use Yelp POI, but that can't be the only POI data they use. They have to use multiple POI sources. Since you have worked for "one of the biggest" you should know that often the POI data is wrong or off. There's a reason why many companies like Google and Verizon provide a way for users to correct lat/long. For example, Verizon's customers can fix the location of their business. Google's map editing tool lets users fix it. I've used mapquest, mapinfo, yahoo, google, mappoint and a few other minor ones. As a developer I've done quality control by comparing the results of multiple systems to validate the error percent. Sometimes one system is correct and all the others are off.
Clearly apple's search implementation is partly to blame, but the problem is far from simple. Given you have experience, your flame towards apple is hyperbole. I've seen errors in every single map software I've used. When I looked at OSS GIS source code to get a better understanding of the internals, it was very clear to me the problem is very complex.
It's going to take a lot of time for apple to fix all the issues given how tough the problem is. In terms of POI, I know some yellow/white page systems use stock navteq/teleatlas POI as a base and add to it. For thinks airports, train stations, monuments and other big landmarks they tend to be ok from first hand experience. Smaller thinks like museums, movie theaters and other stuff it's quite bad. For example, a movieplex at a big mall.