It's something you feel uncomfortable mentioning much, in the "don't give people any ideas" category, but it has long puzzled me why cars/buses/trucks were not used more for indiscriminate terrorist attacks. Bombs are tricky and guns aren't available in much of the world. Vehicles are easy to obtain. Much easier to strap a massive vehicle to yourself and plunge it into the crowd. We can be glad that the last few people to do this weren't very smart about it. I guess the only "bad" thing from a would-be terrorist's perspective is that such attacks aren't likely to create as much chaos and disruption. No one's going to call for screening people who can use vehicles. Roads aren't going to be shut down for more than a day.
Generally, if people are willing to get caught/die in the act, it's impossible to stop these things from happening.
