It's not nonsense
Let's illustrate with a swingeing tarriff. I can buy a 500Mb daily pass for £2 on Three. That's to an end user, inclusive of VAT. I would be deeply surprised if Apple couldn't arrange a wholesale data rate which was a 1/3 or 1/4 of that.
So a 4Mb song download would cost me a massive 1.6p to download. It's almost background noise and would certainly be recouped from people who purchase more stuff than they would otherwise. It's even less for books which are smaller.
Larger files like video might need further consideration but I'm sure Apple could produce a smaller "on the go" version of a movie / show for immediate viewing with a free upgrade to the full version when they attached to a PC, or just calculate and pass the cost onto the consumer at checkout.
Operators would make money by billing Apple for usage by their customers. Apple could also sweeten (or offset the bills) by selling PAYG / subscription broadband packs from the store that the operator would take a cut from.
The same applies to Sony's NGP device too. Same principle applies there too. Probably more so since Sony could flog a game for €30 and more easily swallow the download cost.
Simply put there is a massive money to be made from devices which provide seamless, hassle free 3G connectivity out of the box at least for the basic online services of the device. OTOH devices that require users to screw around with sims and payplans and all the rest of that hassle won't anywhere close to the same amount of money.