Are modern laws causing the dead beat dad problem?

I agree with you but I think the biggest factor is the existence of welfare programmes that make it more comfortable to live as a single parent than in a couple (financially). Naturally this encourages men to think that they don't need to stick around after the birth if they don't want to and the mother might prefer to go it alone too. This is feminist socialism in action. The matriarchal State tries to take over from fathers.