In areas where there isn’t a dedicated U-turn lane, you have to use the left-turn lane if you want to make a U-turn. You just have to work with what’s available since not all roads are wide enough to have a separate U-turn lane.
I used to complain about drivers in front of me making U-turns and causing me to miss the light. In some cases, it can even lead to rear-end collisions. But then I found myself doing the exact same thing…
So what’s the proper etiquette here? What do you all do? Wave? Honk? (Probably not a great idea where I live since everyone honks anyway.)


SImple solution is to just go into the turn slow. This gives a hint to the car behind you that you might be doing something beyond a left turn, and reaction time for any traffic that you may have to yield for (whether or not they legally have the right-of-way). Once you start turning more it ought to be obvious.
Of course lots of accidents are from obvious situations that could have been avoided, but not doing a legal U-turn isn’t going to fix stupid people.