alt Hacker News> I have never worked anywhere with the L4/L5/whatever crap. No one I have worked with has either. It sounds downright dystopian that people are reduced to a basically a number (if you leave out the L).
This inevitably happens in any large organization. People just have positions like "Department Head" or "Chief Something-Something" instead of numbers.
If anything, engineering/research organizations are unusual because in "traditional" organizations your growth is basically linked to the number of people you direct. In technical orgs, you can be an individual contributor and be at a higher level than many managers.
At Amazon, level is public. Microsoft, only the title (Senior etc) is visible not the precise level is visible is my impression. At Google, it can be public but apparently can also be hidden. At Facebook it's always hidden.
I'm interviewing engineers right now, it is tough to judge what their current level mapping is especially if they come from Facebook. You can guesstimate from their resume accomplishments and tenure but the rest is just interview performance or asking directly - there are staff engineers that get there from 3 years out of college and there are seniors that are at that level for a decade.