Why do programs take up so much space in the Storage section, when in reality they take up much less?

Question

macOS

Answer 1

For some reason, you have a slightly different window than mine, in particular, there is no "Manage" button, but I will tell you my version.
The first window (small) considers it very strange and rude, probably for the sake of speed, but after clicking on Manage (where detailed data is displayed), the first window updates the data, which radically changes the situation. I show two screenshots.
In your case, the "Programs" section apparently also includes "System"

Answer 2

Versions, history.