You obviously dont understand how this whole thing works. A simple search on the internet would solved all this.

WiFi devices do not send out GPS coordinate. So how does it work? (I will include Google here because Maps is based on Google version but Apple did have their own WiFi database collection).

Actually, what Google and Apple are doing is collecting a database of WiFi hotspots, routers etc, through our Iphones, Ipad 3G, Android phones and tablets. What it does is actually acquiring some basic router info such as MAC address (which is unique for each device) coupled with signal strength etc, and then mark the location with the help of the GPS chip in our Iphones, Ipad 3G, Android phones and tablets. What WiFi Ipad does is gather the router info that it can find in the surrounding area and compare that to the WiFi database in Apple (or even Google perhaps?). It calculate the signal strength that its currently receiving, compared to the records in database, to guess where you are. If you are in an area where the WiFi devices havent been added to the database, it wont work.

One of the reason why it works better at certain place like US, is because Google has a team of mobile tracking van, going around everyday to collect such info which is why Google is now being targeted in US for violating privacy.

Of course, this is based on what I understand from online reading. What Im not sure is what trigger the data collection to activate. Is it when we launched map application or everytime the wifi is activated, on our GPS enabled phones and tablets.