It might be worth noting here that the domestic automakers learned a long time ago that building cars to order is not cost effective. You can still do it, but they'd rather not.
Who'd they learn this from? The Japanese. You can't order a Japanese car like you want, never could. You tell the dealer what you want, and they find one like that in dealer stock somewhere.
Build to order is great if you're Ferrari, but Tesla is not Ferrari. Tesla is aiming for much higher volumes, and this strategy flies in the face of Musk's desire to put an electric car in every garage. The manpower and logistics costs to do so in their current manner would be staggering.
I grow weary of this talk that Tesla is different and changing the world doing things their own way. The reason things are done the way they are is because everyone's had 100-plus years to figure out the most efficient way to build and distribute automobiles in volume. The entire rest of the world is not wrong, all in the same manner. It doesn't make sense.
The Japanese are noted for their efficiencies. Take note.