Why didn't Rihanna learn about Israel and Palestine the first time she performed there in 2010? This heavily publicized raid on ships carrying humanitarian aid and construction materials happened only a day after her concert, she must've heard about it.
Gaga is probably aware of where she's touring and what's happening but regarding the state of career she's in right now it's NOT the thing she personally worries about. Madonna would but then again, she always tries to be politically involved so it's kind of her signature thing at a tour.