Signaling before changing lanes

I have been driving in Miami, FL the past 3 days and I can’t believe how so many people don’t signal when they are lane changing or turning. So I googled if the law requires it in Florida and here is what I found:

Section 316.155 of Florida Statutes sets forths the times when a turn signal is required.  Any vehicle turning right or left or changing lanes, must signal an intention to turn for at least 100 feet prior to turning or changing lanes.  Visually speaking, 100 feet is about the length of six cars lined up bumper to bumper.
The purpose of the turn signal is to let other drivers know you are about to turn.  Turning on the signal after you have already stepped on your brakes is too late.

This made me wonder about what would happen if we were to signal/communicate our intentions in our regular life before we do something, especially things that are going to affect others?