Because most drivers don't drive in a way where they are trying to hit someone.
But many drive in a way that hitting people is likely
On Friday I had a driver get way too close to me and he reacted by pulling sharply away, this was on the approach to tower bridge from the north, which is a sketchy junction anyway.
So we pull away from the lights and as we're crossing the bridge the idiot who nearly hit me already is driving about 12" off my back wheel, while we're doing approx 20mph across the bridge, eventually the driver decided they needed to overtake me, despite me doing the speed limit and only having about 1-2 car lengths between me and the vehicle in front, also moving at the same speed, they decided to pass where there's a traffic island 🤦
Some people are just shit drivers, they're the ones that kill people. I have lights on my bike, I have lights on my bag, which has a big reflective panel, the rear triangle on my bike is painted so that the whole section glows under direct light.
All of my collisions have been in daylight and I wear brightly coloured clothes, albeit not hi vis