system
Given the following post, respond as if you're commenting on Reddit:
human
[Mirror's Edge] If runners are such a problem, why don't they just have a city ordinance to enclose all rooftops or otherwise make them inaccessible?

The city appears to have the totalitarian level control to do it, judging by how much the city already conforms to a very specific theme.
gpt
I can think of a few reasons. Firstly, that would be a massive and pricy undertaking, and even totalitarian states can't do massive construction work without incurring cost. 

More likely though, is that taking such an action would acknowledge that they feel that the runners are a threat/beyond the control of the state, which could be seen as a sign of weakness and encourage more people to question and rebel against the establishment. 

And finally, it's possible that the state is also using the rooftops for enough things, like surveillance, giving troops the high ground when civil problems like protests occur. This might make it less appealing to make the roofs harder to traverse and reposition on.