When zero hours were set up they intended for seasonal and casual labour and there was initially few thousand. Now they are in the millions and there intention is to avoid paying employee benefits such as holiday and sick pay. Some companies have changed there ways on rights but there are a number who haven't. When you have people like that **** Mike Ashley employing most of his staff on ZHC you know that someone is taking the piss.
People on zero hours contracts have the exact same rights and holiday entitlements as anyone else. There is a legal requirement to give people holidays based upon the hours they do regardless of the contracts they are on. With a full time contract you are just saying that person does 37 hours a week and that is how they calculate it. There is no actual difference in the contract though other than that.
If the hours aren't regular as with zero hours then holidays are accrued on a rolling average so if you average 48 hours a week you get paid/given the paid holidays for 48 hours a week. If you don't then the company is breaking the law.
With sick pay etc it doesn't matter, every company has to abide by the law or else they are breaking it. Zero hour contracts have the same minimum rights to sick pay or whatever the same a full time contract would. Employment law covers all employment and not just full time/part time contracts.