Depends on the town and the teenagers but random violent assault isn’t unheard of, they have some serious cultural/behavioural/psychological issues. They know the police are stretched too thin to respond to calls so they run riot.
Someone glanced at them? Fair game for a wind up or pretext for a “fight” Didn’t glance at them? Doesn’t matter, one of them was in the mood anyway…
I can’t take that ranking seriously, it has Ireland and Australia safer than Japan, and Italy, France and the UK safer than South Korea. It’s just a survey of random people’s feelings - apparently people who don’t know the countries in question
For example here’s another survey showing a massive difference: https://www.numbeo.com/crime/compare_cities.jsp?country1=United+Kingdom&country2=South+Korea&city1=London&city2=Seoul&tracking=getDispatchComparison
And here’s a comparison of crime rate numbers showing most of your top twenty safest countries as less safe than most East Asian countries
https://www.macrotrends.net/countries/KOR/south-korea/crime-rate-statistics
This is all on average of course