The music thing is, I think, a related phenomenon I'll call the demolition man effect. Most people now are so weak and nonconfrontational that someone willing to break social norms can just walk all over them. This is because nobody wants to stand up for themselves or more fundamentally rock the boat.

The shamelessness thing is similar but fundamentally different in that it gets a following. Everyone thinks the kid/boomer without headphones is an ass, they just don't say it.