The site has h1b in the URL. So it surely is about pay in country. Out of country its Groucho Marx territory (inside of a dog, it's too dark to see)
The site does not report on the C-suites, and I suggest on the next tier down. I wish that those people were more transparent about their renumeration but historically its been veiled. Once your pay is a matter for the board, it may or may not be available depending on the nature of the company. Privately owned I don't think have obligations to report renumeration.
They could be underpaying immigrants, but that's unlikely, given that it's illegal and they have a lot of attention on them.