Why cant sodium borohydride (NaBH4) reduce carboxylic acids or esters?

NaBH4 cannot reduce these compounds into alcohols but LiAlH4 can. Sources I have read say that this is because NaBH4 is less reactive than LiAlH4 and that is fine, only my intuition tells me that a carbonyl carbon on a carboxylic acid/ester should be MORE electrophilic than a carbonyl carbon on an aldehyde/ketone... show more NaBH4 cannot reduce these compounds into alcohols but LiAlH4 can. Sources I have read say that this is because NaBH4 is less reactive than LiAlH4 and that is fine, only my intuition tells me that a carbonyl carbon on a carboxylic acid/ester should be MORE electrophilic than a carbonyl carbon on an aldehyde/ketone due to oxygen's electron-withdrawing effects. Why is it that a carbonyl carbon on an aldehyde/ketone is MORE electrophilic than a carbonyl carbon of a carboxylic acid/ester? Gracias.
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