People are used to signs for everything. >don't touch coffee it's HOT
Ever noticed that on the canisters in restaurants for tea and coffee dispensers? Someone got rich over it, they sued, the judge agreed, gave em money.
So if the hot spring doesn't clearly have a label that says "HOT DO NOT TOUCH" people will inevitably jump in due to the signs that brought them into the world. It's something similar with Chinese people dying in the city that were raised to be rice farmers, they drop right into elevator shafts and get hit by cars a lot and stuff. It just happens.