This is true of GDP as well, since GDP only includes final goods. I.e. if a farmer produces wheat, and the wheat is then used to produce bread, the farmer -> baker transaction is excluded from GDP. Only the baker -> consumer transaction counts towards GDP.
If you want to try and measure utility, your metric should be based on consumption - e.g. mean(log(after tax consumption)). Income isn't utility, it's only potential utility.
If we used income, your metric would unfairly penalize volatile income. I.e., a person with a stable income of $50k/year would be considered 70% better than a person who earns $100k then $0k (saving $50k in the first year and spending it in the second while having an identical lifestyle.