Especially Germany and the U.K., but there are other active communities.
Also, in the U.S., the Nominatim instance setup on openstreetmap.org mostly falls back to address range data imported from Tiger. That data isn't really part of OSM. It gives great coverage, but there are some limits to the accuracy.
But the internet is global. It might work correctly for you when testing, but somebody in another country finds your app utterly useless.
Even if Google Maps has worse data for some areas than OSM, globally it's far more consistent.
Given that there's far, far cheaper options for mapping than Google while still providing excellent data (ArcGIS comes to mind), if you're building a commercial product with an international market in mind you're still better off using a commercial GIS solution
This appears to be based on a misunderstanding; the OSM project isn't an app released by a company, instead it's a global community creating a map dataset, somewhat similar to Wikipedia.
If the data in your country or local area isn't good, then please consider becoming a contributor to OSM and edit the map. By making the OSM better, you can help solve those consistency problems and improve the experience for the growing number of people who are using it - whether directly or via companies like DoubleMap.
Being a contributor is nice and fuzzy, but not a commercially viable option. If my customer says "I can't find this town on the map", I'm hardly going to tell them to drive out and map it themselves.
Who knows what will happen in Australia, but a thing I see happening in the U.S. is people starting to use OSM for whatever and then investing effort in fixing their immediate problems. So there is some sort of hand wavy tipping point that has been reached.
And when it comes to websites there are even more of those.
Not to mention that more and more apps use data that only OSM provides.