My hubby and myself are in the small minority my kids aren't ever out of our sight not even for a second, unless they are in bed asleep, I can only speak for our kids but I know what kind of trouble they can get into even in a few seconds I'm not saying this is what works for everyone but it works for us
Wow. I just can't imagine that. What if they run into different rooms for a second? I have one child and it's very hard to keep up with him, most days. I don't know how I'd keep TWO in my sight 24/7 for years on end without going batty! Or do you have everything gated off still?

Strangely enough, my son still sleeps with us so although he is not in our SIGHT overnight, we are right there with him. We don't co-sleep because of this, but I would worry more about someone snatching him in the night than I would about him playing trains in the next room during the day. But that is just my personal opinion. Also, he doesn't really "get into trouble" when he plays by himself. He's a pretty independent, smart kid and he tends to avoid danger out of pure instinct, for the most part!

He will usually come to me if he needs any type of assistance. If he gets really quiet in the other room, I will go check. ALL PARENTS know the "too quiet means something is up" rule.

But if he's in there singing and playing, I feel no need to be staring right at him the whole time. I think independent play is extremely important for young children. I don't really enjoy hovering; it makes me feel uncomfortable and isn't good for his development, IMO. I think that can lead to anxiety in kids, when they feel like they aren't capable of doing ANYTHING without strict supervision and assistance. YMM(AOD)V.
As to all the bickering about whether the woman in the OP was adequately supervising her child, if the news article quoted seriously misstated some of the facts, then I would certainly reconsider my opinion. The way I read it, the woman was just a few feet away, dropping coins in a SA bucket, snapping a few quick pictures, and it didn't take more than a few minutes. Maybe that's not the case. BUT IF SHE WAS RIGHT THERE WITHIN SIGHT/QUICK REACH OF THE CAR, my opinion stands. It may not be the absolute safest/best thing to have done, but in no way should it be criminal. I was also unaware of her State laws regarding this type of situation, so perhaps it really is a criminal offense even if she WAS right there. In that case, I would simply say that I don't think it should be. And I still don't believe EVERY cop is honorable/infallible and never inflates a situation beyond what it really is, for personal reasons or due to bias.
ETA: Went back and read the whole thread...
As for the "social worker with no kids" debate, let me share my insight:
1. I worked as a therapist/social worker for years before coming a SAHM, so I feel I can speak with some authority on this issue.
2. Social workers usually DO know better than the parents they interact with, because generally those parents are involved in the system for some type of abuse or neglect. This often leads to a perception by social workers (at least the ones I worked with) that they necessarily know more than ALL parents, which is totally untrue, IMO. Social workers who are parents know not all parents are clueless/abusive/neglectful/inappropriate. Social workers who are not parents don't have the grounding experience of coming home to a relatively normal nuclear family at the end of each day and knowing that most people do okay, and their kids turn out more or less okay. And I'm not knocking that at all, because I was in that boat for many years. I'm just sayin'...you really DO get so used to judging parents in that job, that it becomes a knee-jerk reaction. I mean, you're PAID to evaluate their parenting skills! The gossip about them as human beings, however, is done free of charge and usually in the office with no clients around. :X
3. Whether I consider the advice/perspective of a childless or childfree person depends on a few factors. If the person is explaining their reaction or philosophy about something in a calm, rational, and reasonable manner, then I might give it a second thought. If the person is spouting something ridiculous that any parent in his/her right mind would know is impossible IN REAL LIFE WITH A REAL CHILD, and further states that anyone who doesn't is LESS OF A PARENT, then I roll my eyes and move on. And I did that back when I didn't have kids, because I am one of four and know some things just plain don't happen the way you want them to!
4. There is a lot of emotional stress involved in social work. Tough, endless, underpaid work, and sometimes you feel like you're not getting anywhere or really helping anyone. It's a very demanding job and MORE THAN A FEW of my former co-workers either burnt out and quit or had outright breakdowns during the course of my employment in several agencies. Seriously! My former boss even committed suicide!!!!!! So I try not to judge people with a job like that when they flip out. I know how draining it can be.