Although 4 times out of 5 it's the mom who walked away (plenty of times with reason, I'm sure). Do we have a problem in America with lazy irresponsible dads? Yes, for sure, but not to the extent most people say. We also have a problem that there are of a lot understandably embittered fathers who are culturally informed that being male makes them unsuitable parents, had no idea how to be a good father but tried anyway, love their kids but hardly ever get to see them and meanwhile as further punishment for not being able to spend much time with them, is also forced to hand over a large amount of his money to the mother so that she doesn't have to find a job. And then a separate but related problem is that if you're a man who is poor and can barely afford to support his family, the government rewards you financially if you don't live with your family.
There are injustices. The system isn't perfect by any means. However, most of these situations aren't moms divorcing the dads. They are dads who never married the moms and never tried to.