> Companies may now have a direct incentive to have their lowest income earners be outsourced/contracted

The median was presumably chosen because it's relatively harder to shift in this way. Although this depends on the exact pay distribution of your company, you'd expect getting rid of people from the bottom to change the median person but not typically change the median value.

(This is also a mature enough problem that I'd expect other provision in the law to prevent this - are we sure it doesn't include outsourced workforce pay?)