People SMILE AT things seen for a variety of reasons, not always because of being pleased or happy. Laughing at somebody else's troubles is a common trait among humanity though:
　「Our grins are not as simple as they seem. There are a myriad different ways to smile – and some of them can conceal some less than happy feelings. …Landis wanted to know if certain experiences, such as pain or shock, always elicited the same facial expressions. And he was prepared to inflict them in order to find out. He sat his subjects down in comfortable chairs, then painted lines on their faces so that he could better see their grimaces. Over the course of three hours, they were repeatedly photographed while being subjected to a series of bizarre and unpleasant pranks, including placing fireworks under their seats and electrocuting their hands while they felt around in a bucket of slimy frogs. The climax came when he fetched a live white rat on a tray and asked them to cut off its head with a butcher's knife. Landis' methods were certainly unethical, but perhaps the most uneasy revelation was what he discovered. Even during the most violent tasks, the most common reaction wasn't to cry or rage – it was to smile. He wrote: 'So far as this experiment goes I have found no expression other than a smile, which was present in enough photographs to be considered as typical of any situation.'…Today reminders to 'smile' are ubiquitous, printed on fridge magnets, adverts, self-help books and occasionally hurled at us by well-meaning strangers. Those who smile often are thought of as more likeable, competent, approachable, friendly and attractive. But the truth is far more sinister. Of 19 different types of smile, only six occur when we're having a good time. The rest happen when we're in pain, embarrassed, uncomfortable, horrified or even miserable. A smile may mean contempt, anger or incredulity, that we're lying or that we've lost.」
　　[　https://www.bbc.com/future/story/20170407-why-all-smiles-are-not-the-same 2019-10-04　]　
　Sometimes we smile in order to force ourselves to feel better:
　「When our brains feel happy, endorphins are produced and neuronal signals are transmitted to your facial muscles to trigger a smile. This is the start of the positive feedback loop of happiness. When our smiling muscles contract, they fire a signal back to the brain, stimulating our reward system, and further increasing our level of happy hormones, or endorphins. In short, when our brain feels happy, we smile. When we smile, our brain feels happier.」
　　[　https://www.britishcouncil.org/voices-magazine/famelab-whats-science-behind-smile 2019-10-04　]　
　So, simply the thought that somebody else's troubles are not one' own can cause a SMILE based on a physiological reaction. Consider SAD SMILES and the reasons for them, such as a natural impulse to help someone else in trouble to feel better:「A Swedish study found that it is indeed difficult to keep a long face when you look at people who are smiling at you. …Seeing people smile stimulates our mirror [neurons] to suppress our facial muscle control, and trigger a smile. 'You smile, I smile' is actually a scientific fact…. Furthermore, smiling also brings health benefits, like reducing anxiety, as well as lowering your blood pressure and heart rate.」[　ibid.　].

Modern definitions (that generally disregard history) …excluding politically incorrect concepts and other meanings deemed offensive today; may list only pigeonholed definitions, euphemisms, or meaningless mnemonics)
Chinese: to smile at
Unihan extended: to smile at
EDRDG: laugh; smile