Good question. This is based on anecdotal data from people in the service industry (customer service, food service).
I've read many accounts where older clients become very very upset when told something they don't like. It causes safety problems for the workers. These clients are more likely to throw a tantrum and expect to get their way after behaving badly. They are more likely to take their rage out on the worker, as if it were a personal issue.
The service industry is somewhat to blame, for years this behavior was rewarded as "the customer is always right". And companies assumed lowly workers would continue accepting abuse as part of their job. We understand now that workers are actually people. Abuse is no longer accepted as a way to get special treatment, but clients who have been behaving this way for years find it hard to adapt. Tantrums were/are their only "problem-solving" skill.
Depends on their personal prejudices towards people who are younger than them. Some generations expected young people to automatically submit to their authority, simply because they were older (even complete strangers, even if they were abusive). If they were raised that way it makes sense they would have the same expectation of young people now.
They felt powerless growing up, and now feel they earned the right to expect obedience from others because they are the most "senior" in the room, regardless of their behavior.
We now acknowledge that women and even young people have the right to their own bodies. It is their right to not want to be touched. It is their right to tell someone "no, leave me alone", even with attitude!
I'm seeing many comments that blame Miu's violence on the teen boys, for "riling him up". As if Miu is not responsible for his actions. That perspective is problematic for justice.
All IMO.