Cell Phone Etiquette

Why are some people so obscenely lacking in self-awareness that they don't realize that they're yelling into their cell phones while in line at the supermarket, in an elevator or, as I faced today, on a treadmill in the middle of a quiet gym floor?!  It's aggravating to say the least. The woman next to me was yakking at her mother while bobbing up and down on the machine in a half-assed attempt at getting in shape.  She was expending far too much hot air out of her yap while talking to even remotely be able to build up a decent cardio heart rate.  I'm not the most polite person in the world on many levels, but when it comes to cell phones I try my best to go into a corner or outside or anywhere there aren't people to annoy.  I don't even want everyone hearing my half of the conversation in a whispered voice, let alone shouting it in the middle of a crowded room.  This woman was talking so loudly that I'm not sure she even needed a cell phone to be heard on the other end. 

^^^^ This dreadful woman ^^^^

obviously has not googled and read up on the plethora of websites offering tips on improving  CELL PHONE ETIQUETTE!