If the Malaysian Airlines flight crashed, and if 239 people on board were killed, that's less than 2 hours' death toll for cars crashes.

But the bigger danger of cars may be that they encourage people to get less exercise.

In September 2001, car crashes killed more Americans than terrorist attacks did. Terrorists have killed only a handful of Americans since then, but cars do it again every month. So why are Americans so scared of terrorists and not scared of cars?

Partly it is due to human psychological tendencies. Many victims from one event attract more attention than many separate events with the same total number of victims. Violence attracts attention too. Conversely, whether you have a car crash is partly under your own control, which reduces the fear caused by that danger.

This is exacerbated by the mainstream media's exploitation of fear of terrorists, and by the written and voice announcements in trains and buses reminding us to be very afraid of the (probably nonexistent) terrorists.