Not directly, but there have been estimates. I don't remember where I read them though, so I can't give them to you. IIRC digital still only amounts to somewhere between 10 and 20% of gaming purchases.
It is a service. You get the game, you never have to hunt for a patch or worry about what condition your CD will be in five years down the road, usually the only DRM involved is logging into the account. They do the work and spend the moneys to make sure all this works right, that you get good download speeds, that the installer works properly, etc. What does the retail store sell you? A box with a cd and a manual. They don't care in the slightest what happens after that.
So I'd say I get more for the same dollar amount.
Meh, hunt for a patch. Google pretty much does the hunting for you and that is if you are too lazy to just go to the publisher or developers website. Not a service I am interested in actually paying for. I have CDs that worked fine after 15-20 years, though I can't say the same for the companies that published them. Almoast all of them are belly up now so I guess if there was service attched to them, I'd be worse off without a CD than I am now. Having to have an account to play a game at all is pretty much the ultimate form of DRM (see previous sentence).
I don't know why you would be so elaborate with the digital distribution and so basic with the retail. Retail versions aren't just about what's in the box either. That product is shipped, stocked and displayed. Removing the box isn't just removing the box, it's also removing services attached to that box.
I can browse Amazon or walk into any local discount store and find a lot of the games sold on steam for half the price steam sells it. It's ridiculously expensive. Hell, most new releases aren't even sold at the suggested price at release at the e-tailer and B&M stores.
I can see you want to turn this into a digital distribution vs retail pricing. As in one has to be better than the other, and naturally, only one opinion can "win". I really don't care either way, the pricing with software is messed up. You have games that cost millions to make and publish being sold for 40 USD and then you have a game that is little more than the rehash of some of these value/casual games being sold for 20. Thre is clearly no link to between production costs and actual price. Heck even in casual game markets you have World of Goo selling for 6.99 at BigFishGames and 19.99 on steam. You have Guild Wars being sold at Newegg for 9.99 and other places the expansion alone is 2-3 times that amount. Now some of that is sales, some of it is not and all the while you have developers claiming they aren't getting enough money, publishers who advertise their DRM as a service and a justification not to be competitive and behind the scenes are these contracts about who gets what for each dollar.
The fact of the matter is it costs money to produce cds, make those boxes and make those manuals, ship them to the store and get shelf space. All those costs are essentially dissipated by digital distribution and the cost of the servers to allow those downloads to happen is even't close to publication costs and yet the consumers aren't seeing the savings, and if the developers aren't getting that extra money then yes, there is a problem with software pricing and how the dollars are divided on the way to deliver said products.