There are many obstacles and problems with being a single parent. The child does not have the stable home life that it needs to grow and mature if they are in such a situation. The parent should go to classes to learn how to raise the child better with the limited resources that they have.
Going on the pro person so your saying that if your a single parent its just by default unstable. I know people with single parents that completely stable with fulfilling lives and perfectly normal mind spaces. Its a shame that someone from i'm guessing from a two parent doesn't understand life outside their bubble.
I don't think it would be fair to require a single parent to be required to complete a course on single parenting, the vast majority of single parents will be competent and fine parents to these children without having to attend a course, also many of these parents are already going to be busy with working a job and caring for a child there may not be time to attend a course like this.
The nature of parenting is that everyone has to go through growing pains before becoming the best parent they can be. Single parents already have enough on their plate as it is to worry about dealing with a parenting class. Hopefully they have support systems to get through any tough times.
Single parents should not be forced to go through and complete parenting classes that are put on by the government. When the government tries to mandate things. it only gets more messed up and the costs go out of control. The best thing is for adults to not get pregnant unless married.
Some single parents are just as effective, if not more so, than married parents. To single them out to attend parenting courses is akin to stating that single parents are not as good as parents as married parents. If single parents are required to attend parenting classes, then all parents should be required to attend parenting classes.