In the Netherlands authorities do not believe in masks. Their mantra is: keep distance, desinfect hands, stay at home when you have a cough, hay fever, copd, etc.
The Dutch authorities hold the opinion that the disadvantage of a mask is the faux feeling of safety it provides. It invites someone to take greater risks: "I am wearing a mask". But when a mask catches aerosols from air and people touch it, they infect themselves, especially when a mask is re-used again.
In public transport a mask is required because breaking the distance rule is almost unavoidable, especially when entering or leaving a bus, train, metro, etc. For the rest no masks are required. It is rare to spot a mask here. Queen Máxima is very in line with Dutch policy.