Care to state why? If you were to buy 100% of the company you'd...

Care to state why?

If you were to buy 100% of the company you'd be paying much more than just the equity value on balance sheet. So the return you would realise on the money you invested (in buying the whole company) would be much lower than the ROE.

Also, ROE uses net profit (NPAT) which is affected buy variations in tax rate and funding between companies. So your not necessrily comparing apples to apples with ROE.