I love it when readers help each other. I'm sorry I didn't think of it. If that mother would walk in my shoes for just one day, she would immediately abandon the practice. I don't think I need to go on. I realize children have different levels of maturity, but we must never forget that they are indeed children.
Some states have laws that prohibit children under a certain age being left alone.
In Pennsylvania, the age is 12. Please print this so that some parent who may not have considered all the consequences of leaving a child alone may see it. If it saves just one child from injury, it will be worth it. I like your idea of getting a teen-ager to stay until the mother returns from work. If she has not already done so, the mother should also look into organized after-school activities for children of working parents.