Yes, all the cleaners work via the regulation 'dienstverlening aan huis'. This regulation makes it possible to have a cleaner for a maximum of 3 days per week without any hassle. More information can be found on the Dutch government website.
The standard hourly rate for a cleaner is from €14,-. You can choose the hourly rate yourself, with a minimum of €14,-. The 8% holiday pay is already included in the hourly rate.