An another fact to consider is the contradiction in the legislation. While someone can legally sell "sexuals services", it is illegal to buy them. That contradiction is a open door to contestation at the court based on the fact that a right is given but the means to use it is not. It is why we never see case involving consenting adults beeing prosecuted in courts. Thoses cases being prosecuted involved (at the best of my knowledge) some aggravatings factors such as violence, non-consenting acts, drugs, minors, fraud, etc.
The governement and the supreme court don't want another case (British Colombia 2012) involving sex workers associations asking the respect of their right to work for a living and having to officially rule in favor of them by decriminalizing customers. Or to go back, against all the jugements of the 30-40 last years and criminalized sex workers again. Thus the actual statu quo on that situation.
There is nothing to gain from a political point of view to go against customers who respects the rules, the notion of consent and draw no complaints from anyone.