You're thinking way too hard about this. My car does the same thing. It's normal.

Your fuel sending unit has to pull gas from the bottom, and push it out the top of the tank. If the level is low, it takes longer to build up the pressure to move the gas.

You'll notice with the fuel level low, and after cranking the car to start it, you can immediately shut it off, wait a minute, and it starts immediately. That's because the pressure is held in the fuel line after you shut the car off, and when you start it the second time, you don't have to wait for the pressure to build up. If you let it sit for a while, the pressure releases back into the tank.