That's because an accident and a traffic violation are different. Minor accidents are usually handled without police intervention, and this is by design.
See my other comment: he pulled out without looking because he was in the middle of cutting up other road users (me in this case). That’s driving without due care and attention which is a traffic violation in the U.K.
The police don’t care. What mechanism will put him in jail?
"Driving without due care and attention" sounds like a statute that has a much more specific interpretation than you think, and the police probably aren't the ones who misinterpreted that here. "Careless driving" and "reckless driving" are against the law in many states in the US, but both actually have very specific interpretations that are not entirely contained in the text of the statute. This is the joy of living in a common law country.
Things like running red lights, not stopping at stop signs, and speeding are much easier for laypeople to judge, and it sounds like none of that was happening here.
Yes, drivers who blow through red lights and stop signs like the bad actor cyclists do will find themselves in jail (on reckless driving charges, incidentally) pretty fast. You're trying to compare apples and oranges here: a driver who happened to not see someone while driving (because they were driving more aggressively than you liked) vs. people who regularly flout traffic laws.
One group kills and maims five people a day (drivers) and your problem is with the group that doesn’t. In fact, you’ll fight tooth and nail to defend the driving that put a man in hospital by choosing not to look for hazards.
This isn’t “more aggressively than I like,” this is a man put in hospital because a driver chose to ignore the UK official guidance on how to drive. Official guidance, I might add, that you must learn as part of your driving course.
