Does the school have a particulay handwriting style? If so it may not be general neatness that qualifies for the 'licence', but correct formation, joining in the right place etc.
With the maths working out it is important that they do show them in full and on the same sheet, as they are used in assessment (by which I mean teacher assessments, not just SATs)
But this teachers approach does seem very tactless - the work should never have been sent home with another child's name on, and the 'pen licence' seems very over-formalised.