Benzene and proton in 1H NMR
The aldehyde is both deshielded by reduction in electron density about the carbon it is bonded to through electron withdrawal and by the magnetic anisotropy of the double bond. Although a benzylic hydrogen is slightly more deshielded than the hydrogen attached to a two electron pi bond like a carbonyl or an alkene, it does not also have electron density withdrawn from its adjacent carbon. Generally electron withdrawal through resonance is more important than inductive electron withdrawal, so the difference in chemical shift between an aldehyde and an alkene will be greater than the difference in chemical shift between the proton proton geminal to a halogen in  a halogen-substituted alkene and the proton in its unsubstituted analogue. All that is to say the additive effects of resonance electron withdrawal and magnetic anisotropy make an aldehyde proton more shifted than a benzylic proton.