It's an issue in many Western countries, where we've seemingly become risk-averse to the point where it's causing more harm than good.
You can, but it's a crime, much like buying banned drugs etc.
> do they expect a dad to raise a kid that is not his?
Yes.
You just need a court order to do a paternity test, they're not banned but regulated by law.
This seems to have led to the pendulum swinging too much in the opposite direction, where they now seemingly force foster kids to meet their biological parents against the kid's will[2]...
[1]: https://rett24.no/articles/norge-felt-i-ni-nye-barnevernsake...
[2]: https://www.nrk.no/norge/mener-fosterbarn-presses-til-skadel...