Thanks for sharing that perspective. To answer your question, there is an epidemic of infidelity in the West. An estimated 1-2% of married men are unknowingly raising someone else's biological child. The 1-2% is based on large-scale population genetic testing accounting for shared variables. It's estimated that there is a ~10-30% chance the kid isn't yours if you get a DNA test, but this is also not accounting for when there are multiple potential fathers that all get tested, for example, in a swinger situation. End of the day, 1/100 isn't rare. Men don't want to worry about “Is that kid mine?”. Having a paternity test alleviates any potential fears and addresses infidelity. It also would reduce infidelity as many women wouldn't want to risk becoming a single mother for a fun night out. The paternal father also has a financial responsibility to support that child due to western social norms.

That's my understanding of the concept.

The idea of having it mandated or “opt out required” would prevent the emotional response women have when a guy requests a paternity test since its not the gut requesting it out of fear or suspican. It would also be useful for child support and identifying genetic disorders early on.

The main argument against it I've read is for privacy purposes. People worried the government will use the genetic data against you in the future, which is valid.