This is a common occurence. Happens here in the US too.
You are correct. That has been the law here for many decades. “The Law presumes Virtue, not Bastardy.” I still have that in my police academy notes from over 30 years ago.
Unless the husband can PROVE non-access (e.g. in solitary confinement with no ‘conjugal’ visits) he is responsible, regardless of what paternity tests might say.
Also, once you start paying, you have to keep paying, regardless of what paternity tests say. Judges say it isn’t about the father or his rights, it is about making sure that the child has financial support. Tag, you’re IT!
No, it isn’t Just, but it is the Law. The two are not the same.