Couriers not stopping on single yellow line - is this common?

the plod don’t give a damn, ‘cos the alternative will piss off everyone.

Like other emergency services it’s perfectly legal.

Looking at the guidance for the Edinburgh pavement parking ban emergency services only get an exemption for an emergency call not a blanket exemption

In Edinburgh the pavement parking ban has been a  huge success.  Round my way which is a very old street layout many streets you had to walk in the road.  Now the pavements are clear.  a lot of extra yellow lines were put down as well so narrow streets now only have parking one side on the road rather than two sides on the pavement.  folk got used to it very quickly