Belgian hygiene

I was having a coffee at Wall Street Café in Rue de la Loi before going to an interview at DG MARKT, and had to do my thing before I moved on. Standing by the sink at the loo I witnessed a sign instructing all staff of the café to wash their hands after having used the toilet. In this part of the world do we actually need to instruct people to wash their hands? Should not that be taken as a given?