I would guess brand perception might play into it too. I know I've read before (can't find a source though) about a concept in economics where even if you can afford to price your product/service super low, you shouldn't because customers will perceive your product of lower quality.
suppose netflix had an ala carte option, and the shitty straight-to-dvd movies and shows were $0.25 to watch, but later block busters were $5-$10 per view. If you see too many $0.25 shows on your screen, you will (I think) begin to perceive netflix as a vendor of crappy, cheap content, which ultimately hurts their whole brand.
If due to piracy, newer entertainment options, etc., the number of people who digitally rent a movie is smaller, and the cost to make a movie is the same (or higher), then it doesn't matter whether blockbuster had employees, the costs could be similar to getting the digital version.
In other words, the differences in operating costs between digital Netflix and store-based Blockbuster might not be the major factor of the actual cost (and thus the price to rent).