Additionally:
- having a Github project matters, but nobody looks into it the code.( nobody looked into mine, because I was never asked about it.)
- The ethnicity match matters, a interviewer from India will reject you outright if you are a local American.
- about the the luck part, I have one interesting observation. When teams are desperate the bar is much more lower. Give enough interviews and you can be assured that atleast one of them is for a position where they immediately need someone. The downside to this, is that once you get the job, you will notice that desperation for candidates most probably stemmed from a project not meeting it's deadline and the team was hoping to throw in more bodies to salvage it. You will be under tremendous pressure to deliver the undeliverable. Do not let this get to you.
Just because they didn't say anything does not mean they didn't look. I look and take notes about what I see, but in the actual interviews I very rarely talk about their GitHub. I mostly just stick to the script.
Not saying this never happens, but I doubt it happens at any kind of company one would WANT to work for.
Could it be a phenomenon that superficially may look similar: discrimination due to different educational backgrounds? Foreign employees at tech companies often have degrees from quite selective colleges — to some extent it's a prerequisite of the visa process. In contrast, local candidates don't always have college degrees, and if they do, they're not always from top tier colleges (e.g. at some point, the university that the most Apple employees graduated from was San Jose State: https://www.businessinsider.com/best-schools-to-get-a-job-at... ).
That's not to say that this is a good hiring criterion. But it's not quite as deranged as hiring on ethnicity.
It takes luck, skill, and a personal match between you and a set of people at a company. At the end of the day both parties must feel like they have a good match.
Re: Tech interviews, unless you pore time into things like leet code and "cracking the code interview" tech screen will always just be psudo random.