It all looks very sad and aimed at maximising ticket revenue. I was at a meeting yesterday listening to the agent for possibly the biggest solo artist in the world right now and he explained how they have put in place their own system to stop secondary sales and touts hoovering up tickets for forthcoming tour. They spent 10 days going through purchases manually to verify 1.1m tickets. Every ticket is personally named and the T&C at time of purchase made it clear any resale attempt would result in cancellation. They also threatened all secondary sellers with legal action if any attempted to list tickets. Only Viagogo ignored this - as they ignore anything legal. They expect some 95% plus of tickets to find fans at face value. And if you can't go and need to sell, they have their own outlet to allow face value only sales.
The problem for U2, even if they wanted to do something similar, is that contractually they may be constrained by the deal with Live Nation. I expect they are still in pay back mode and the contract hasn't got much time left to run. The Live Nation model is designed to maximise revenue across all areas which is why they own all aspects, including the band.