Why does the CAS V3 not have model answers

Because the CAS V3 has item specific BARS (Behaviourally Anchored Rating Scales) they can be seen as a guideline to score. Therefore model answers are not necessary. Also model answers at times could restrict the assessor to expect only certain responses from a candidate and then rating any other responses as negative. The item specific BARS allow the individuality of each candidate while still ensuring standardisation of the scoring.