The house size seems to be more “tv magic” than an actual defined house of infinite size.

The upstairs hallway is sometimes a normal short one, and other times is long enough to land a space shuttle.

They even make a joke about this in the Ghostbasket episode. Bandit is pretending to be a realtor and Chilli remarks that the house is a bit small, to which he replies "it's bigger on the inside"

There is a replica of the house that was built in real life.

I've been in the bluey house. It is approximately 8600ft (800m sq). The work-life balance that the family has doesn't seem particularly odd when it comes to Australian households.

Australia, you say?

https://www.youtube.com/watch?v=tV7JPC2FuNs

There's a real house?

I think you need to look at it as parents spending 8-10 minute periods of time with their kids. In fact there is an episode where the Dad has to go to work and he spends a short amount of time playing with them before he has to go.