The Greek people didn't take out the loans
No, but they voted for the bad policies that resulted in having to take out loans.
Those of us having children are the only ones helping you have all the social welfare programs (pensions and Social Security, etc.) after you stop working.
Ahahaha. First off, those programs are pyramid schemes and unsustainable. Secondly, if those of us who choose not to have kids weren't forced to subsidize you (schools, tax credits / deductions, etc), we could invest it and earn far more than we'd ever potentially see from mismanaged entitlement programs.
The couple decided between them to have the kid, you fucking moron.
Sometimes. More times than not it's the woman saying "We're having a kid or I'm divorcing you and taking everything" or, more commonly, she just stops taking her birth control without telling him and then "Wow, I can't believe this happened!".
You don't want kids? Just as bad - you'll be considered married in CoP if you simply live with her for a long time
Not in the US. Almost all states in the US have eliminated "common law" marriage (though existing ones aren't nullified).