Confusion on electron withdrawing and donating effects of alkoxy, amide, ester groups

According to this picture from uworld, the OR portion of an ester is considered electron withdrawing, and the nitrogen portion of an amide is considered electron donating. I suppose I can see how, in the amide, the carbonyl oxygen is more electronegative than the amide nitrogen, thus it pulls electron density, making the Nitrogen donating.

However, why is an ester considered electron withdrawing? Both the Nitrogen and the oxygen of amides and esters, respectively, have lone pairs of...

Confusion on electron withdrawing and donating effects of alkoxy, amide, ester groups