The scope of my argument here is clearly based on past income in the US (that's why I mention W2 income).
I'm fairly confident a medical doctor in the US is paid more than a janitor.
Now, you can make an argument about whether a doctor in a rural area is more valuable than a software engineer in SF but there is an NIW (National Interest Waiver) category that can be utilized to grant residency.
Funnily, in the current system, janitors and meat packers (from other countries) get their green cards earlier than doctors and engineers from India [1,2]
