I have no experience of UK nurseries.
My children are all going through the Belgium school education system, and it is very structured right from age two and a half. Many children will have attended a creche from a very young age (3 or 4 months) which is also very structured.
That does not mean that they do not play. In fact they spend most of their time playing. They are not expected to learn to read and write until age six.
But from a very young age, they are taught how to listen, how to follow instructions, how to walk along the pavement holding each others hands.
All the nursery school teachers are graduate trained and there is a ratio of about 1/20 or 1/24. There are no teaching assistants although the classes do share a care assistant if a child needs help with the toilet.
It is noticable in Belgium how well behaved school children are. It's common to see large groups of very small children walking along the pavement with just one adult per 20 children or so.
The children are trained from a very young age to do are they are told and to follow the 'pack'. They are expected to go to the toilet when they are told, to sit down and sing when they are told, to line up when they are told. They are taught to be polite. At lunchtime, they are not encouraged to talk while eating. The children play and make crafts, but it is very much the teacher who is in charge. There are long breaktimes and long school holidays.
I am sure that this system would not work for all children, but my children have all coped fine. They have thrived in the structure and have all enjoyed school. A critisism of the system is that it does not encourage individuality. But most children I know attend many out of school activies (or not!) to express their individuality.
If a child has extra needs, there may be special learning support for them - we are in the process of applying for this for my child who has mild SN.