Shouldn't be too surprising. There's a reason that Sony jumped on board the pay to play online service model, despite many fans predicting they never would. It prints money. And now even Nintendo is following suit, though late to the party but also offering a much better (but lower, which impacts these numbers) price.
So they're all raking in money from their storefronts and Sony is selling more consoles, which means more gamers, which means more PS+ subs, which means more money than the others.