How do I make my MacBook's logical resolution the same as its physical one?

My MacBook has 2,880 × 1,800 physical, R/G/B pixels in its display (1800p). However, Mac OS renders at 3840 × 2400 virtual pixels (4k). I don't know or care why, but I do know that this makes things unnecessarily blurry for me. It doesn't do this with external displays, so I know the OS is capable of outputting to the native resolution. How do I force Mac OS to output to the native resolution of its integrated display?

Below is an illustration of what bothers me the most. The left is a photograph (physical resolution of 1800p) and the right is a screenshot (virtual resolution of 4k).

Note the 2px left vertical in the photo has one clean, white line on the left, and one faded white-to-black line on the right. The screenshot shows it's actually rendering a 3px-wide left vertical, and all the pixels should be cleanly white.