Why does adding acetic acid eliminate streaks in TLC

Usually I've seen triethylamine added to eliminate streaking by amines because silica gel is acidic and the amines get protonated, however I guess you could use acetic acid to force a very acidic group to stay protonated, and thus keep its band narrow.

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But for an acidic compound, I can't think of anything besides acetic acid protonating the acidic compound in case it becomes deprotonated.

Very good.  Now.  Consider this: what do you expect from a compound with no acidic or basic groups, and what do you expect if you you have a slightly deprotonated compound mixed with fully protonated in the same lane on a plate?

Thx for the reply. I understand how bases react with the slightly acidic silica gel and that triethylamine reacts with the silica gel to prevent this from happening, however, I am not entirely certain how acetic acid or formic acid can prevent streak. Because my instructor told me to use acetic acid in the developing solvent for an acidic or very polar compound. I understand that the acetic acid makes a developing solution containing ethyl acetate and hexane more polar which pushes the polar compound, thus reducing streak. But for an acidic compound, I can't think of anything besides acetic acid protonating the acidic compound in case it becomes deprotonated.