Title text:
"You legs may have a comparative advantage at running, but we arms have a competitive advantage at swinging hammers, so unless you accept that we're the dominant limbs and stop hogging the oxygen, that running advantage won't be around for long."
Transcript:
Transcript will show once it’s been added to explainxkcd.com
Source: https://xkcd.com/3290/
Or they're if cheaper because of subsidies, for example China's cars.