Where? They'd have to be dozens of them around the ground to cover all parts of the stadium and going from level 3 would take the entire halftime period. They'd have to close and secure the entire outer perimeter of the grounds before opening any access point. (which I don't even think they physically can do) It's a security issue above anything else. They can open away sections because the area outside is generally enclosed, can't do that for home matches.
It's 2 hours, nobody should be in a position where they literally cannot go 2 hours without one. This should be something for City matters to push, it's an easy win to get City to clamp down on it.