You are conflating multiple issues among them legality, ethics and civility.
You are correct, it is illegal to park in a handicap area without a sticker or tag. People do however. I believe people should speak up when they encounter such behavior. You apparently do not.
People obtain or use stickers that they have no right to. That is also illegal and again I am willing to speak up and you are not.
People who are legally entitled to a sticker and to park in a handicap space - still have an ethical issue each time they chose park as to whether they need to park in the space, if, like the woman in this post, her condition varies significantly through time. That situation does not appear to be applicable to your husband so there is no issue. For this woman though, she can hardly complain when somebody sees her on a “go to the gym” day and raises a question. I agree that the way she raised the issue was over-the-top, but I have no problem with her raising the issue.
I am against anyone without a sticker using a handicap parking space (if someone is obviously disabled and is awaiting a tag, I would not balk). That is illegal. You don’t get a tag without a doctor’s certificate of NEED. Just because someone is not in a wheelchair or using an assistive device, does mean they don’t need a handicap spot. There are people with lung conditions, heart conditions, or endurance deficits that may look, to you, perfectly fine, but they aren’t. Try a little compassion, or at least empathy. You never know what private hell someone else is going through.