What I don't understand is why I never hear of free commercial networks. If you avoid downloading game, video and music files, then it's very difficult to download more than a Gigabyte of data a month. You simply charge everybody who uses over a Gigabyte. Also, I've heard that the less time someone has been on the Internet, the more likely they are to click on random advertisements, so that's helpful as well.

So, basically, if you downloaded less than a Gig of data, you'd get free Internet, and then charge competitive prices for each successive Gigabyte.

Could someone please explain to me what's wrong with that model? Because, I honestly don't understand why I've never heard of anything similar.

Ballymun and Ballyfermot are not liable to cause a lot of noise as free wi-fi sites as they are Dublin's equivalent of the projects in the US, or the most run-down council estates in the country. Usage levels will not be high I suspect.