It's a form of social domination, the people that do this are literal animals
But the sharp, piercing tone of tin(n)y (and somehow super-amplified) phone speakers, playing particularly grating videos or loud video calls, all at max volume, seems optimized for maximum irritation. And it's often adults, who presumably would not usually shout but are nonetheless talking very loudly into their max volume facetime calls.
I would probably find it annoying if everyone walked around listening to sports games on small radios, but it is a rare occurrence so I tend to be more surprised that sports radio (not to mention AM radio itself) still exists.