I've just listened and they completely missed the point - of course it's easy to police the salary cap if everyone declares all their expenses. However if you don't record the expense then there's plenty which could be excluded.
Are you suggesting that clubs are simply giving money to players and not declaring it?
That's an accusation that they aren't just being creative with accounting but are in flagrant breach of the rules.
Unless every club is doing it, I can't work out why there wouldn't be more fuss made by those that aren't doing so. If Quins truly thought that Saracens were, off the books, bunging their players hundreds of thousands of pounds (and then those players were committing tax fraud by not declaring the income), they would be shouting it from the rooftops.
Not to mention that players talk - if Itoje, Kruis, George etc are on England duty and rubbing shoulders with players from other clubs there's no way that the cheeky £200k they are getting on the side, illegally, doesn't get leaked out.