It’s simple actuarial fact. Left turns cause accidents. Minimizing them on busy thoroughfares allows traffic to move without fear of being cut off by some idiot trying to go to Target. And it simplifies decision making (and lets face it, not everyone is a great driver) by ushering turners to traffic signals where right-of-way is clearly given.
lots of things are dangerous in life, i guess that’s why we need the gov’t to make sure we don’t hurt ourselves....