A second order effect of criminalization of walking is a culture that does not value walkability. People are so accustomed to non walkability and so unaccustomed to groups of people strolling about that it does not even occur to them to think about what a loss this is.
The claim still works without the element of racism. In the extreme car-centric areas of the US you're regarded a weirdo for walking anywhere by members of your own race.
You could bet you that those four people would have the same thing happen to them in Japan's walkable cities as well. It is nothing to do with walkable cities.
at least have enough courage to admit that 4 teenagers would make you nervous. there's nothing wrong with being alert. teenagers can be dangerous and unpredictable. the dividing line IMO, would be behaving preemptively in such a scenario.
4 teenagers would not make me nervous. Happens many times per day for many of us. Parent comments are talking about something different than "common sense" or "being alert". Profiling is a real thing that many people have to deal with.