The way it's batches that are empty and not empty seats here and there suggests it's not auto cup ST holders just not turning up.
Maybe dodgy resale sites getting hold of batches of tickets and not being able to sell them at daft prices?
Went the toilets near block 10 at HT and for the first time ever I didn't have to queue. Also loads of space on the concourse around there between 10 and 11