Don't blame Miami.
I am originally from the Northeast and attended many events up there. I lived in the area of the Yale Music School so the usual concert goer was well educated and well behaved.
Outside of that there were several concerts by community groups and school groups. Many friends and relatives attended these concerts and most had almost no idea of what was going on OR, what constituted proper behavior. There is little education about formal music in America these days and therefore, little respect.
I do not know what your choice of venues might be but I can say that my fondest memories of classical music happened at the British Museum of Art lunch series on the Yale campus and I would have to look hard to match that environment or those patrons.
When you come to a fork in the road, take it.
My goodness! I've never seen anything like that, not even at high school concerts. The only time I've ever been disturbed by an audience was when I was performing a concert of opera choruses with my (non-professional) choir, and an audience member was wheeled in who suffered a severe breathing impairment causing him to loudly snort every time he took a breath. It echoed throughout the hall for the entire concert.