That's the real crux of it, I've yet to see an advocate of the 'it's not speed that's the problem but inappropriate speed' that doesn't also consider that they have superior driving skills. The amount of accidents where speed is a significant factor would indicate that this isn't the case. A persons superior driving skills, judgement and awareness are only superior until they're not. Whether it's over confidence, an off day, someone elses fault or an alien spaceship landing in front of them.
Now I know that all those muppets are not really good drivers and you're the real deal...but we only have your word and judgement on that and some would rather trust to speed limits than those.
OK - how's this then: I'm at best an average driver*.
How does the 'Speed kills' mantra help me in an urban environment when I want to retune my radio? Should I just slow down a bit?
How does it help me when overtaking a cyclist and there's not enough room? Should I do it slower so that I can squeeze past at a safe speed?
I guess it's fine for a cyclist to ride on a busy pavement so long as they go slowly?
It's a pointless, unhelpful bit of 'advice' that's chanted by people who would like a snappy way to attack motorists that can't be applied to cyclists.
The reality is more complex, and once again, I've heard Clarkson (and even the character he plays on his
entertainment show Top Gear) say this again and again.
*I believe I'm a good motorcyclist though. I feel much more aware of the road and always think the car drivers are out to get me. 20 (er rather more than 20 now I think of it) years of biking and one single accident. Which happened to happen when a car pulled into me at about 15 miles an hour while I was filtering. He was in the wrong and his insurance paid full costs.