Usually, when children are young they have small problems and therefore their problems will always seem easier.
It may be that when children grow into adults, parents find it difficult to help their children with their problems, because they’re dealing with adult problems. That part for any parent isn’t easy and can take years of practice to master, even for themselves.
It’s may also not be easy for parents to help their children understand how to perceive and resolve their problems, because problem solving isn’t an overnight fix. It can take days or even weeks for us to know how to solve a problem.
At the same time, it may also be difficult for parents; particularly if they’re trying to help and their children aren’t living at home full time. Out of sight, out of mind. That part of parenting also comes with the territory.