"Excessive speed" in the statistics is purely based on posted speed limit. The way posted speed limits are set in the US is not based on safety.
That's an opinion. Any source to back that up? The limits are set based on safety and flow considerations, with safety taking precedent.
""Excessive speed" in the statistics is purely based on posted speed limit."
Not true. This can include going too fast for conditions, such as in snow. Or exceeding the recommended speed for a turn, even if you're going the posted speed limit.
Your interpretations seem very biased so far. I'd love to see your data/facts and not just opinion.
Speeds of motorists in normal conditions
Traffic volume
Roadway type (e.g., interstate, freeway, city street)
Roadway features (e.g., curves, hills, number of lanes)
Roadway setting (e.g., urban, rural, residential, woodland, farmland)
Number and spacing of driveways or intersections
Sight distances
Presence of on-street parking
Pedestrian or bicyclist activity
Crash history
Pavement condition
You need to advocate for street redesign, then.
In California, most speed limits have a relation to the median speed that drivers drive on the roadway. If you want them to drive slower, you need to design the roads so that they drive slower.
Unfortunately, you will be fighting the local residents who don't want to spend extra time on every task because their local roads are so slow.