People regularly getting stabbed in trains doesn't feel like a technological problem. Seems like there are two attractors in the mass transit space: Attractor

People regularly getting stabbed in trains doesn't feel like a technological problem. Seems like there are two attractors in the mass transit space: Attractor 1: The mass transit is safe and clean. Everyone uses it, because it is convenient. Because everyone uses it, people care about keeping it safe, clean, and convenient. Attractor 2: The mass transit is dirty and dangerous. Only poor people use it, because they have no other choice; all middle-class people use cars. Because no one important uses mass transit, no one really cares about making it less dirty and less dangerous. From what I heard, the former attractor seems more frequent in Europe, the latter in USA. There are also other things involved in the attractors, such as width of roads, sizes of blocks, whether sidewalks exist or not, etc. These would be even more resistant to change.