Crying is not prima facie evidence of abuse. Often, quite the opposite.
My family might as well be the one you're talking about. My son cries at the drop of a hat. One of the main reasons we homeschool now is because when he was at public school he literally cried for the last hour or two almost every day. However, indulging him so he never cried for long would be more damaging than letting him cry as much as he wants.
One of our major goals for him, which we consider much more important than academic goals, is to teach him socially-acceptable ways to self-regulate his emotional responses, so he will be able to function in a job. He can't do that without at least some practice handling disappointment. It is extremely difficult to find the right balance with him.
His emotional issues are very draining on us as parents, and we lose our tempers more than I'd like to admit. The fact you never hear a parent means she should probably be sainted.
Our oldest daughter has cerebral palsy. She wakes up in severe pain. In order not to be in pain all day, she requires a series of extremely painful stretches. This causes a lot of screaming, but she thanks us afterward.
Our other daughter is typical both emotionally and physically. She rarely cries for long, and it's almost always for reasons that appropriately require our immediate intervention. Sometimes, we try to think what it would be like to be a person who only has experience with kids like her. How would such a person perceive our other children?
Before adding to this mother's burdens, I would suggest getting to know the family better. Yes, there could be neglect or abuse going on, but most likely it's just the ups and downs of a normal family.