From an evolutionary perspective, I suppose it would be considered a positive thing to see someone else trip (even when it's staged). Another explanation is that socio-economic factors could influence someone's perspective on others; resulting in different responses. Lastly, there could be a link between age and (the development of) empathy.
Perhaps we're all familiar with the feeling of some tragic or dramatic situation making us laugh in a context. Something dramatic happened, someone made a joke about it or a joke came to our mind, or simply the situation itself seemed funny. At the same time we felt bad about finding the situation or the context funny. It's also not uncommon to find similar motives, being often an exaggerated drama, in the comedy genre. Why tragic or dramatic situations can be funny if they're not affecting us directly? How thick is the line between drama and comedy?