I'm surprised about the comments people make about the 30/70 split between Apple and developers. It's almost like no one on this board remembers (knows) what it's like (or used to be like) to get your software on a retail store shelf.
When I was the buyer for a small, independently owned retail computer store back in the mid to late nineties, all of our software and supplies were purchased from a distributor like Ingram/Micro D. The distributors supplied a catalog of products they distributed and you would pick and chose the products you wanted to stock. If one distributor didn't have a product you wanted, you shopped another distributor. If the product was available from multiple distributors, you contact the buyer and negotiate the best deal you could get. Margins on software was typically between 25 and 50%. The larger your store, the more buying power you had, the better your margins. Our store typically dealt with 2-3 primary distributors for all the product we had to sell. We dealt with the hardware companies like Apple and IBM directly. Occasionally, we were prohibited from buying certain software applications because of requirements by the vender (a grey market for these products developed because of this).
If a small startup company, say Quark, wanted to sell their new desktop publishing application to us (we had our store in Boulder), the president or vice president would come by after jumping through a few of our hoops, to give us a demo, tell us about their promotions, give us demo copies, offer to train our sales reps, negotiate margins, offer exclusivity deals, and set up buying terms (we order the product, get net 60 and get to return unsold product after so many months). More often than not, we told them we were interested but only if they could negotiate a deal with one of our distributors because, our buying power, terms, bills we had to pay, all made it easier to deal with just a few distributors rather directly with the companies themselves. Fundamentally, getting your product on a store shelf hasn't changed much since those days. It is still basically the same where I used to work at Microcenter but the number of brick and mortar/Mom & Pop stores isn't what it used to be in the 80's and 90's. In fact, it's probably even more competitive now than it every used to be.
The bottom line, not even considering all the hoops a developer has to jump through for this, they are going to give up upwards of 60% of the retail cost of the product just to get it into a distributor. They'll have to have financing to do that, manufacturing and customer returns to deal with as well. There is a lot more infrastructure costs by far than those dealing with a 30/70 split with Apple. I'm just surprised no one else though about it sooner.