Of course. Remote developers tend to be more senior. Once you control for that, I'd be surprised if this still holds true, given that the FAANGs tend to pay a high share of the highest salaries and they tend to not allow remote work.
Thanks, yes this is an important point which I cover later in the analysis:
"Even once I control for various observable factors (including age, experience, hours worked, size of employer, programming languages, and more), fully-remote software developers earn 9.4% more than developers who never or only rarely work remotely."
You're probably right, but consider the other side. If you remove the FAANGs from consideration (a heavy weight on the non-remote side of the scales) then the remote work premium would look even better.