I've no idea whether Robbie Williams' management really did sell marked-up tickets to his shows via resale sites as the BBC are claiming.
This I do know. If you're managing a hot act you know that there's a big difference between the price your artist is comfortable with charging and the amount the market will pay. It might be twice as much.
If people are going to pay double the standard price for tickets you can either watch that money go to wicked scalpers (or averagely shrewd members of the public who buy two lots and sell one in order to pay for their evening out); or you can get some of it for your artist.
I'm not saying it's right or desirable but I can understand it.