The reaction referred to is the nucleophilic acyl substitution reaction, where the nucleophile is a carboxylate ion and the electrophile is the ester. I am having a difficult time visualizing why this cannot occur.
The reaction you are asking about is a carboxylate plus an ester reacting to form an anhydride plus an alcohol. The reverse reaction, making an ester from an alcohol and an anhydride, is one commonly performed in teaching labs.
So the equilibrium lies on the side of the ester. The principle of micro-reversibility would suggest that this reaction can go in either direction, but you would have trouble detecting formation of the anhydride and alcohol from the carboxylate and ester because of where the equilibrium lies.