I line manage 30 people who are on zero hour contracts. I have been looking in to getting them a better deal, but about 4 of them have actually said to me they like things as they are, because although they don't get sickness/holiday pay (actually their hourly rate does incorporate a holiday premium, so it's not actually correct to say they don't get paid holiday), they like that they can basically choose when they want to go away, and tell me they're not available for work.