Wrong end of the stick?

So J K Rowling has donated £1m to the Labour Party - nobody's business but her own, but I do take issue with her reasons (or one of them) for so doing. She pointed to David Cameron's stated intention to re-introduce tax perks for married couples, which she sees as discriminatory towards single mothers, of which she was one. I think she misses the point. There is plenty of evidence that, as far as society is concerned, marriage is A Good Thing. Married couples are healthier and wealthier than their non-married counterparts - it's not clear why this is so, but it is a statistical fact that it is. Children born in wedlock (and isn't that a deliciously old-fashioned expression?) are far more likely to steer clear of anti-social behaviour and a life of crime, far more likely to get a job and contribute to society rather than be a drain on it, and far more likely to look after their parents and relatives in old age rather than leave that responsibility to the state. And then they are far more likely to get married themselves, and so perpetuate these benefits. Given this is so, it is perfectly proper for Government to use whatever tools it has - taxation being the main one - to encourage people to get married. This has nowt to do with single parents - it doesn't really have anything to do with marriage per se, it is simply encouraging behaviour which will benefit us all.