> obvious engineering solution is to ban pedestrians and design for cars only.

No, the obvious engineering solution is to ban cars, the worst means of transporting humans ever conceived, and design for pedestrians only. If we want motorized vehicles sharing space anywhere near pedestrians, they should be operated only by highly trained professionals (e.g. taxi drivers with retest licensing requirements, commercial truck drivers, bus drivers, etc), or, by vehicles on rails (subways, trolleys, trains).