In happens mainly in the low-level gameplay. Beginners tend to take everything possible. 
Btw, the standard abbreviation is QGD, not QGR.
QGA vs QGR
Sort:
Indeed. I would wonder what sort of traps or "chaotic "games you refer to in your assertion? If as you say, white is faced with, if black accepts the "gambit"? Maybe in your experience some players seem unprepared for it, is your question? I personally like playing against the QGA. But I'm very experienced and give myself a slight plus vs QGA positions. Transposing to Slav-type configurations or trying to hold on to the c pawn is always a theme in what you'd call, "balanced". Nothing tactical or chaotic in my opinion. Of course I'm not saying the QGA is busted, rather that it is far easier to play against than Orthodox QGD lines because of Central Control and more mobility for white's pieces.
@Yigor You're right! 
It is QGD, it was a "mental translation" from my language... we say refused, not declined...
@najdorf96 I agree with you! as white, QGA is welcome. What i don't get it, is from black perspective. As black you exchange a central pawn for the white c pawn, and let white have d4/e4. the black rook at a8 is a target for so many traps. in many positions you can fork the king and the a8 rook, broken the black castle and winning the rook. the black queen flank in a couple of moves are almost destroyed, without pawn chain and pieces in the wrong places. That's why i asked what is the goal of QGA from the black player perspective. I played even stronger players than i am, and, as white, didn't felt any problems in the openning...
Very sound. Not too theory intense. Generally fairly free piece play. It's an excellent opening. Look how many great players have played it at one time or another. There are things that can go wrong like any opening; most of the things you mention though will only occur if Black is completely clueless.
@JamesColeman Thank you very much for your comment! So, if i get it correctly, it is easier than QGD because has less theory, and, if correctly played gives balanced position? As white my plans goes to a4 trying to pick the tower in pawn exchange, queen in the a8 tower diagonal to pick the tower and the combo knight/bishop to get the fork, break castle and pick the tower. The only "problem" i feel is the overdevelopment of my pieces in queen's flank and the delay in the castle kingside. I'll try to find some GM's games with QGA to understand the tatics behind it. But i can say that i'd never play that, and never never with a stronger player like yourself, because i feel i would be crushed in no time. The best line IMO for black is to forget the black c4 pawn and not try to defend it, but if i want to do so, why give up the center in the first place?
Why anyone accept the gambit in QGA with so many traps, cahotic game and loss of central control? For surprise the opponent? Because many people are not used that someone really accept the gambit and aren't prepared for it? There are really any advantage in that capture? In my games is at most, a balanced opening for black...