Yes, Vector Art has to be drawn (or re-drawn) in the computer.
Once it is re-drawn, the computer 'describes' the various shapes with math data.
So . . . when you scale the art, the computer 'does the math' to reduce or enlarge the image with no loss of detail or resolution.
A scan (or Pixel art) on the other hand, is made up of thousands of small squares of color or Black-n-White. The higher the resolution, the more 'squares' per inch.
Once the scaned image is in the computer - that's all the information the computer has. You can make something crisper by reducing it. I.E. a 150 dots-per-inch scan reduced at 50% is now 300 dpi to the computer (and printer). But, if you enlarge it, your 150 dpi image at 200% is now only 75 dpi.
Think of the difference between a photograph and a Sunday Cartoon. The photograph represents a 'high resolution image' whereas the Cartoon would be 'low resolution'.
On the cartoon, you can actually see the various dots of color where the photo appears seamless.
This comparison is a gross example - but you get the idea.
Later . . .