55 vs 75 no difference?

Yeah if you think a 75mph crash will kill you but you get to walk away unharmed from a 55MPH crash, I have really bad news for you.

speeding cause less wrecks than driving 'slowly' in the left lane?

That is correct. Speeding is involved in a minority of accidents, and is the cause of even less. Over the course of a decade, I’ve seen two fatalities due to speeding, they didn’t harm anyone but themselves in the process, and both were on residential boulevards, not the freeway. I’ve seen far more caused by erratic unpredictable driving, driving too slow for traffic, and turning into traffic.

I’m a man who’s been fortunate enough to have saved dozens of lives that were almost ended by people like you that become road hazards on purpose, and less fortunately the witness of far more innocent people losing their lives because of drivers like yourself. People like you have caused far more injury and death than any speeders could hope to. Speeders are nothing more than a convenient scapegoat. As long as they themselves are not driving erratically or switching lanes unpredictably, they’re of minuscule concern. There are countries with freeways that have speed limits more than twice the U.S. and they do just fine.