No, there is another reason. If there was a 'real' zebra pedestrian crossing (pedestrians always have priority) in a very busy areas cars would never get a chance to go. Also at some points where traffic lights are needed , adding pedestrian crossings not needing lights would be chaotic.As far as I can see, the only reason for push button controlled crossings is because drivers, in their self important schedules, are far too busy and don't stop for pedestrians. Thus drivers are further educated that they don't have to stop unless enforced, by red light, to do so. Hence, we all have to suffer the infuriating time delays inflicted by dumb machine programming.
Common sense and courtesy would work far more efficiently.
Absolutely drivers should be more considerate, and pedestrians should have some degree of priority (as in my light timing suggestion above), but they can't always be given absolute priority.