there was really nothing about the street or traffic design that was the problem
Someone died. There is something wrong with the design.
The driver was going so fast
The street was designed, actively or passively, to allow the driver to travel too fast.
it literally obliterate a steel bus stop
I dont know about this specific bus stop; but in my quick search, the different types of SF bus stops i saw all had sheer bolts. That bus stop may have been literally designed to sheer away from the pavement to reduce damage to cars and/or surrounding infrastructure, an interesting design choice based on what can be inside them.
traffic design had nothing and will do nothing for what happened in this instance
Check out "killed by a traffic engineer" and/or "confessions of a recovering engineer." It might feel like there was nothing wrong with the design; but as with all engineering choices sacrifices and balancing choices needed to be made. This street chose driver comfort and speed over human lives. It may have taken a long time for those small errors to accumulate and align for a death, but they were omnipresent.