Because "A should give way to B" does not imply "B has the right of way over A".

I'm afraid that's just the case in the UK.

> The Highway Code is essential reading for all road users

https://www.gov.uk/guidance/the-highway-code/general-rules-t... in addition states:

> The rules in The Highway Code do not give you the right of way in any circumstance, but they advise you when you should give way to others. Always give way if it can help to avoid an incident.

The point here is just because you think you're in the right, you still have to do your best to avoid conflict. If that means you should give way to someone that should have given way to you, then you should give way.

I think this is really sensible. It puts the emphasis on everyone to avoid accidents and conflict. Nobody has "the right".

Just be nice to everyone...