snip

Yes, a lot of main roads near where I live (Oxfordshire) have recently
been
downgraded to 50 (or are about to be downgraded) "to reduce the number of
traffic accidents". This is solving the right problem in the wrong way: to
avoid collisions, you need to penalise the person who *causes* the
accident,
typically a driver who is on a minor road who pulls out into fast-moving
traffic without assessing its speed or the pedestrian who crosses the road
without regard for the traffic, rather than penalising (by imposing a
draconian speed limit) the driver who is in the right and who has
priority.

/snip

Exactly how does penalising the person who causes the accident by pulling
out into fast moving traffic ACTUALLY HELP ???

Agreed. it might stop them doing it AGAIN - but the FIRST accident they
caused still happened. Perhaps they aren't even around to cause another
accident ! (Darwin has an explanation for that - sadly they often take
others with them).

Slowing the _other_ driver down minimises the kinetic energy when there is a
crash and reduces the probability of _someones_ family having to visit a
morgue to identify a mangled corpse.

If you were the relative of the person who caused the accident by pulling
out into faster-than-expected moving traffic - would you be comfortable with
the consequences - their death, the oncoming vehicle driver (and passengers'
deaths). Isn't slowing down worth it to avoid all that pain?