Hang on a minute guys...... How are you figuring smoothing capacitors on an A.C. circuit? If the meter were fed through a rectifier, then capacitors across the resultant half- or full-wave rectified D.C. would work to let the meter read the effective peak voltage, but if the caps are connected directly from each A.C. line to chassis, they can't act as smoothing capacitors because the polarity is changing 120 times per second. Also, if the meter were being fed rectified power in that case I would expect a reservoir/smoothing cap to be connected directly across the meter terminals.
My guess would be that the capacitors are more likely there to act as a form of suppressor against high frequency transients causing by switching loads, etc.
