"Here's an interesting point though - are 'older' parents more likely to consider bike seats and trailers? That's certainly been my perception from nursery etc"
The answer is yes.
BUT
There are many variable reasons.
The following is a GROSS generalisation.
'Older' parents (eg nearer 30 than 20) - especially first time - are more likely to have 'thought' more, acquired more - house, car, disposable income (or not!)
It's all 'cultural', 'societal' etc. anyone who can afford to own/run a car isn't entirely poor and could (be expected to be able to) afford a bike/seat. But they might not think able to as well as a car.
Might consider that a bike is a sign of poverty (discussions on 'why cycling is middle class' etc. etc. - or perhaps, in a nursery context, "older"!)
Just seeing more people cycling will change things. But there must be plenty of nurseries where no-one arrives by bike.