"Think of the children" when used as an expression refers to the situation in which children are used as an excuse to implement rules which would be otherwise unpalatable. Not every case of protecting kids is a "think of the children" situation.
Quite the contrary, I think. Society has become "soft", for lack of better words. If we had been so risk-averse centuries ago, the industrial revolution would have never happened.
That sort of argument might work well for a time when slavery was a recent memory and children frequently worked in factories instead of going to school. That doesn't mean it works equally well for the present day, or for the kind of future most of us would probably prefer.
I'm confused. You think if we don't let robots break childrens fingers because we insist on proper safety, then the industry of physical chess playing robots might never get off the ground?
We could have had a perfectly good industrial revolution with more mechanical safeguards and less child labor.
If a machine is 20x faster than human labor, and making it safe knocks off 10%, that's fine. And it'll leave you with better employees over time. It's only a problem if you're in a race to the bottom that doesn't care about worker safety.
The industrial revolution and accompanying urbanization lowered birth rates.
Technological progress is not necessarily good for the species, although it can be (c.f. the advent of new agriculture methods creating more food post WW2).
There are tons of rules around these kind of robots in regular work environments for precisely this reason.
Usually there need to be either a physical barrier like a cage or a virtual one like a laser waterfall that detects foreign objects in the robots perimeter and emergency stops it.
These rules were disregarded here.
I used to work in a company were such machines were developed and even a very experienced engineer, working on a prototype, was once hit by it (no serious injuries and safety was improved afterwards) because they can move very fast and in unexpected ways.
These days there are better solutions available (so called cobots) which are designed to be work together in very close proximity with humans whiteout physical separation. They feature very sensitive force sensors and are severely restricted in the way the are allowed to move.
So yes "think of the humans/children" does apply here. This is a solved problems and the operators decided to disregard established procedures and went instead for "flashy and cheap" (cobots are more expensive and slow as molasses)
Although I do agree with you about having an e-stop.