Because its cheaper to install these systems (a simple sensor and a chip), than try to resurrect dead pedestrians

because there are a lot of externalities resulting from car crashes, the burden for which is not paid by the driver, manufacturer, or even their insurer.

Have you considered looking out of the windscreen once in a while?

How many crashes do you think these prevent?

40k deaths per year in the US. A million a year worldwide. A world war worth of deaths every decade.