That's not the same as building in' holiday pay though, F-F. It's simply giving you paid holiday time straight away.
Anyway, it's largely irrelevant as Ruby's employer still needs to be convinced that a zero-hours contract actually exists in the first place:
https://www.theanswerbank.co.uk/Law/Question1701426.html
Publicans traditionally employed many casual bar staff as if they were self-employed, paying them cash-in-hand as a 'contractor' and leaving it up to the individual as to whether or not they informed HMRC about their 'business'. (As nominally self-employed individuals, such bar staff were denied holiday pay and the other employment rights which are aforded to employees).
HMRC have clamped down a lot on such arrangements and most publicans now deduct income tax and National Insurance from the pay of such staff. However it hasn't yet dawned upon a significant minority of publicans that, by offering someone such casual work as an employee, they've
automatically created a zero-hours contract, meaning that they must provide the employee with all the benefits that employed status brings about.
Ruby's employer clearly needs his knuckles rapped!