What makes you think they aren't? Most I've encountered seem to have a fairly wide angle.

Also, the most dangerous road crossings may well be where a cycle path and a parallel major road jointly cross a minor road, especially with the same light timing. The common design flaw of separating the path from the roadway leads drivers to forget that there's another traffic lane they are turning across. It's even worse if cycles and pedestrians are segregated, as drivers can careen blindly into the cycle lane while their attention is focused on the pedestrian crosswalk beyond, meaning bikes are at best in their peripheral vision.