That's probably not the point. Manufacturers have to build their cars for what they can do, but not for what they actually or usually do in "real life." This is why high-speed cars must have stronger brakes, regardless of whether they need them in real life or not.... You have missed my point, which is that - most of the time in real world driving - sports cars and SUVs don't travel at different speeds (regardless of the capability of the sports car).
The worst case scenarios dictate the required strength of the brakes, and these scenarios are just different.