"Government organisations
say that data sourced from government organisations is the best"
Oh really?
Public sector and private organisations in the UK have thumbed their noses at data derived from Web2.0 pushers and information sourced from the, er, wisdom of crowds. A joint survey, conducted by the Association for Geographic Information (AGI) and PriceWaterhouseCoopers LLP, of around 100 UK private and public sector outfits …
This isn't surprising at all. If you've ever tried to work with open street map you'll have seen how "flakey" it is as a service. Frankly if mapping is crucial to your business you want to minimize the risk of downtime and services like this just don't have the guarantees of uptime that are required.
Google is better for uptime and functionality but is INCREDIBLY expensive if you have a successful product. It gets to the point where it's more cost effective to buy the data from the ordnance survey folks and host it yourself. Plus you have to remember that a lot of companies have already bought said data so they are just reusing existing assets.
It's a dataset, a dynamic one, but still only a dataset. You have to build your own service, be it spatial database, tileserver, wms server to host and disseminate the data. Relying on the mapnik tile layer should only be a development option if you want to have a serious application/service at the end.