

Low hood regular cars make peopke fall unto the hood. Tall, vertixsl SUV hoods rather lead to people being pushed under the car in case if a front collision. The latter is much more deadly.
Metal spikes or other stuff extending sideways outwards is obviously a danger towards others and wildly illegal in civilised countries for a reason.
The problem are not the emission standards, the problem is that authorities allowed the huge loophole which allowed to ignore them but only if the vehicle is extra large, wasteful and dangerous.