"We" don't ignore them. Every major government has a body dedicated entirely to automobile safety. In the USA, this is NHSTA - National Highway Safety & Transportation Administration. They maintain an information system of traffic fatality statistics in the USA, called FARS (fatality analysis reporting system). This system is used to determine new safety devices and standards for vehicles and to test their effectiven…
They also have explicit tradeoffs between the changes they make and deaths, proving the article's point.
Plus the guidelines often prioritise speed as an end goal rather than caring about throughput, or the fact that it should be a quiet residential street.
Plus the destruction of transit.
Spending just as much as safe, accessible transport would cost on road widening projects and barely keeping deaths under a high self-declared threshold isn't prioritising safety.