Try a thought experiment. Imagine what your life would be like if it were informed by no comparisons and no expectations. No expectations : a sugar cube might turn into an ice cube. A dropped plate might rise to the ceiling rather than drop to the floor or might remain suspended in space in the exact position in which it slipped from your hand.
You could not compare the size of a table with the size of a car, because comparisons have been eliminated. Nor the size of your clothes with the size of your body. Nor the size of your body with the aperture of a letter box. The experiences of Alice in Wonderland would hardly bear - excuse the word - comparison.
In practical terms life would be unrecognisably different from your present or past experience. The future would be an absolute unknown since no inference from comparison or expectation could provide even the limited use it now has.
I like your question. I have answered with light examples but only to make the serious point that, whatever Hume may have said with urbane and devastating philosophical scepticism about expectation and comparison, he never advised us to abandon either in everyday life. Sensibly enough, I think.