Jan Olieslagers is quite correct. Its the maintenance of this kind of database which is the most difficult part of the process, since it actually requires a phenomenal number of man hours to chase up airfield owners to keep info current - it turns out many of these owners have better things to do than keep their details up to date, and a database owner needs to balance the desire to keep the data useful without cheesing off the providers of that data with constant "friendly reminders"...
In short, its not just an IT problem... Even with the best quality tools that make self-reporting of such details simple and easy, the owners have to actually want to use them. Those who do want to continuously share their details already do with existing guides, and those who don't will probably not be served by a new project - after all, they didn't give their details to existing guides, so why would they do so for a new one?