Since this is a fairly local story, I saw the followup last night. Apparently she was pushing them around a fair in 95-degree F weather with high humidity. To keep the sun off them, she covered them (up to the neck) with one or more afghans.
A police officer walking by heard one of the children wheezing. (Turned out he had a collapsed lung.) Looked in and saw their bright red faces. Told the mother she had to get them out of the heat. She argued with him -- turned into a confrontation. His only recourse to force her to get the kids out of the heat was to arrest her. And the only apropriate charge was child endangerment, which is a felony.
So I'm backing off on my earlier opinion. Though I did qualify it by saying there had to be more to it.