Note: the following is not arguing in favor of the UK policy, but is a general observation.

I seriously doubt that the majority of parents want the state to raise their children for them.

By arguing about irresponsible or lazy parents you are latching on to the first, most convenient thing that seems to make sense to you. But I think that is a mistake because not only does it perpetuate some kind of distorted sense of reality where parents don't care about their children and want to hand off all responsibility for them, but it distracts you from the real causal issues.

The fact is that humans have for millions of years acted in various levels of coordination to raise and look after children as a group. Modern society has made this all sorts of dysfunctional, but it still exists.