It's basically the Gillette model of sales. Flog the razor cheaply, but people will soon enough need new blades. I believe printer companies took it slightly further by actually subsidising the printer cost - hence them doing everything in their power to stop you from using third-party refill cartridges.
Sadly it's true about the original fitted cartridges only being part full in most cases.
Although the model is undoubtedly true, I'm not really that sure that shaving razors have made that much of a technological leap apart from adding ever more razors and calling the "quad" to ever more ridiculous extents. Printers, particularly inkjet/deskjet have made gigantic leaps in technology even in just the last few years.