The one that always gets me is the fact that pedestrians have priority over
vehicles that are turning into or out of a side road. Why should
pedestrians, who normally have to stop at the kerb to wait for a gap in the
traffic (except at zebra crossings and pedstraisn lights, obviously) be
given precedence over vehicles at the most dangerous part of a road, namely
a junction with another road?

Because road users going along a main road have priority over those
turning in or out of side roads - whether either user is a ped. or with
a vehicle is irrelevant.

In practice, might usually rules -

I'd suggest it dosn't really - motorists who 'steal' priority by
threatening to run down anyone who gets in their path are like most
bullies: parasites upon the existence of an (imperfect) level of order
and cooperation. If might really ruled (i.e. anarchy) the vulnerability
of cars to arson, theft & vandalism, either random or as revenge
attacks by disgruntled other road users, would probably make owning one
more trouble than it was worth. (Not a situation I advocate -
personally, I'd prefer a shift towards more order rather than less).

Jon