Bottom line is, LN/U2 expect to make a certain amount of money every time they go onstage, be that in a 10,000 seat arena or a 100,000 seat stadium. Arena shows generate less income due to size, so to compensate they have a lower operating cost and higher ticket prices. Stadium shows make more money, and offer acres of cheap seats for casual fans. A stadium show costs much more money money to produce, but the large numbers of audience members still ensure that their asking price is met, less expenses.
U2 played to 202,000 on 360 in LA. Right, but if in 2009-2011, they played 10 shows at the LA forum, with the I&E pricing structure, they would not have sold 202,000 tickets. They probably would have several nights half full, and only the weekend shows would sell out: