Firstly, I said kids and not small kids. That's important, because working parents of small kids are the ones most likely to have year round provision already. So actually, we're talking overwhelmingly about DC who are 5 plus. Nor did I say anything about 'full time'. There are situations where childcare exists but won't cover full work hours.
And secondly, you as an employer wanting holiday childcare to be available does not magic provision into existence. Well, unless you're an employer of a childcare company I suppose. You can be as outraged as you like, but meanwhile there are some areas where there's nothing at all and others where the provision is shorter hours. I don't need holiday clubs for childcare myself, but the ones in our area are all 9 to 3 or 9.30 to 3.30.
What this means is that in some cases, having the parent working and the DC never present is not one of the choices the employer has. They'd need to either get someone else entirely, which may not even be possible in this job market. Or they accept that the existence of DC and insufficient childcare means the worker is going to be looking after the DC sometimes or taking unpaid parental leave. The least disruptive option for all concerned often involves some time where the child is around at the same time as the parent working. As an employer, you might just have to suck it up.