[Teddy]

In an ester, why is it that the eqivalent hydrogens on the o- side causes there to be more of a chemical shift downfield than that of the equivalent hydrogens on the acid side?

[Winga]

It is because one of the carbon binds directly to O while another one is separated by a carbonyl group.
Therefore, the inductive effect of former one is greater than that of latter one that the proton(s) in H-C-O is more deshielded compare with the proton(s) in H-C-C=O.