They're not paying to be anonymous, they're paying to increase their privacy. Someone like Denise Coates is very rich and famous, but a business woman not a performer. She isolates herself just fine and has a 'relatively normal' life despite there there being many who would like to 'just have a word'. (OK she's about 20x richer than Robbie Williams but the same principle applies). She doesn't travel on public transport with dark glasses on darling or wear a Denise Coates baseball cap.