Redwood: I don't think you read that clip the way I did. It says that this woman suffers from a condition that causes her to have seizures frequently, and when she stepped into the scalding hot shower she had a seisure, collapsed and lay helpless in the tub while 136 degree water sprayed on her unprotected body.
That is hardly "typical". If that woman had checked the water with her hand first and collapsed on the floor, she wouldn't have been scalded.
It takes from 5 to 15 seconds to be scalded by water of 140 and 133 degrees C., respectively. In fact, it takes at least two seconds of exposure to 140 degree water to get a first degree burn, which is the lowest category of burn and which is typically characterized by only redness of the skin and some pain being experienced as a result.
Safety Facts on Scalding Injuries
Tip - Temperature/Time Scald Chart
And, my point is that a normal adult can respond to sticking his hand into a 140 degree shower to check the water temperature well within the time it takes him to say one-mississippi two-mississippi to avoid getting even a first degree burn. If that person walks right into a shower without checking the water temperature, then it's going to take longer for him to get out, but that would only happen once. Thereafter they would check. Personal experience is a wonderful teacher.
The elderly and young children are much more susceptible to scalding from hot water. As a person gets older, not only do they respond more slowly to potential dangers, but their ability to respond quickly and appropriately to the peril is often impaired. Often they become so overwhelmed that their minds are simply not able to think of an appropriate response, however simple it might be. This is why water temperatures in nursing homes will normally be set a lot lower than you would set it at in a typical house. Also, young children and babies are more easily scalded because their skin is thinner than adults, so it's a good idea to turn the water heater temperature down in a house where there's children, especially a newborn who can't explain that the hot water is hurting him/her.
I, too, have inadvertantly filled a bathtub up with hot water instead of a mix to get a comfortable temperature, only to have to drain 10 to 15 gallons of heat. But, people don't get into bathtubs like that because even without testing the temperature of the water first, by the time one foot is half way into the water your brain knows the water is too hot and tells the foot to get the he11 out.
140 degrees is the highest I'd set a water heater. As long as that temperature of water is being used by responsible adults, then I don't consider that to be careless or unreasonable. If there were elderly, mentally impaired or young children using that water, I'd turn the heater down to 120.
Everywhere in between is really a matter of personal choice in my view.
For over 20 years I've had my water heaters set at 135 degrees, and so far no one has complained that the water is too hot. If anything, people complain that their showers aren't hot enough. So, what's a guy to do? The higher water temperature makes for more warm showers every morning so that no one has to make do with a cold one.