I am hoping to get some inputs from both designer and manufacturers  of PCB's on this topic. The issue is when customer specifies finish copper thickness where is the thickness most important. We have several designs with ground area and isolated pads and traces. The customer calls out for finished copper of 0.0026" and does not specify where measurement is to be taken. The total ground area is 15.84 square inches and the total circuit area is 3.36 square inches. Plating up the ground to meet this thickness is almost impossible without the circuits dramatically over plating and holes in this area becoming undersized. I have done some calculations of the current carrying capacity of the trace verses the ground area and the ground can carry 100 times more current carrying capacity than the trace. My question is why would the ground and the trace have to have the same copper thickness? Or does it? My QA department is rejecting everything because the ground does not meet the specification of minimum .0026" while the traces are .0038" to .0042". This is becoming a major problem causing many rejects due to over plate, under etch, traces shorting.
Yes the use of 2oz copper foil would make this easier but have any of you gotten a quote lately on 2oz copper foil. Would appreciate your inputs

Scott B. Westheimer