Google is mostly about backend data processing. Google's front-end effort is nice, but dwarfs in comparison with the backend accomplishments. The same is true for most other businesses. So the demand for backend engineers would definitely be higher. And it's easier to outsource UI than outsource backend, because backend is typically more complex and harder to test and communicate about, so keeping developers closer to business users is even more important in for backend functionality, than for front-end functionality.