Well, I find it hard to believe that €200 - €300 should be "full". That can most certainly not cover the full cost for child care, so there's probably still a significant subsidy by the state even for high earners.
And as the sibling here say you can get rebate for having more kids too.
Having accessible daycare for all means more women can go to work full time which again means higher productivity among the population and more career opportunities for women so it is very important in many areas.
In corona times it is essential to get anything done effectively.
We also have the right in law to daycare, not just an offer if there is room for it.
The actual cost is much higher but is covered by the government, with some adjustments to account for local variations in things such as real-estate costs and similar.
To be clear, I'm in favor of governments taxing for the purpose of providing services of benefit to society. But having the government cover costs does not make those costs go away, it just shifts how people pay for them.
Given that Norway has extremely successful oil and gas investments that doesn't seem right. This is money that the average person would never see anyways. It's not money coming from their taxes back into their pockets.
Of the 1.173,5 bn NOK income in the 2020 national budget, 1.084,8 bn NOK are from taxes and various charges.[2]
[1] - https://en.wikipedia.org/wiki/Government_Pension_Fund_of_Nor... [2] - https://www.statsbudsjettet.no/Statsbudsjettet-2020/Satsinge... (Norwegian)