http://www.expatica.com/nl/news/dutch-news/dutch-ignore-smoking-ban-in-bars-and-clubs_234734.html
The smoking ban in Dutch bars and clubs is being widely ignored, according to the authority responsible for enforcing it. Almost half the cafés in the Netherlands turn a blind eye to smoking customers.
The figures come in a report by the Netherlands Food and Consumer Product Safety Authority NVWA based on inspections between December 2011 and May 2012. They authority says customers are still smoking in 49 percent of bars – around the same proportion as in 2011.
I guess you can say anything is banned but that doesn't mean people have to respect it.