In my company, I think it's roughly 2-3% at L7 or more. It takes really special skills to reach that level, not just years of experience. I don't know how it compares to EM though, but it's a tall ladder!
> those of us happy to go back to IC roles have no trouble finding work
My concern as an IC is ageism. I wish that I can say that when I'm 50+. I feel EMs are a little more immune to that (perhaps more so in Europe where SWEs aren't very well respected).
So even though there are more L7 EMs than SWEs, you might still have an easier time getting to L7 SWE, if you're ready to be an L7 SWE.
Your point about ageism is well-taken. I'm not yet old enough to really feel it, but I have heard it's rough.
That sounds like a positive. As an EM, there's a good chance you'll be promoted to L7 via pure luck - with no abnormal amounts of effort, and with no outstanding talent for management. It sucks if you're in the minority which "deserves" the promo (is super hard working and talented), but for everyone else, it's a free lottery ticket to a higher comp.
Imagine as a simplified analogy, applying to get into Harvard. Imagine Harvard has 1000 spots to fill, and that there are 10,000 applicants with roughly equivalent credentials (because they all have: near perfect test scores, high GPAs, strong extracurriculars, etc.).
In that environment, one might conclude that, for people who successfully get into Harvard, it was 30% their own skill, and 70% "luck" that the they happen to be semi-randomly picked by the admissions committee who could've easily gone with a nearly-equivalent alternative.
So sure, in that environment, "luck" is a factor, but this is by no means a "free lottery ticket" because the near-equivalent applicants had to work hard and be smart to reach the point of being near-equivalents of each other... So it is with promotions in competitive tech companies at least, where good talent is the norm.
Are doctors, lawyers, or surgeons viewed the same way? I don't know those industries well enough to say. Some domains of software are very, very deep and require many years of study and practice.
It feels like the root of SWEs not being fully respected simply comes back to the fact that they aren't considered as part of the org as much as management is.
Those are three very different things with different growth paths. But as someone who went from engineer to entrepreneur and is now on the product side, I can say that software people, almost as a rule, focus on stuff that doesn't matter for promotion. It's really frustrating sometimes.
Modulo pathological things like corporate politics, companies care about profit and loss. Grow the business, make the money roll in, and your chances of advancement approach unity. But far too many software people devote their time to "honing their tools", when, to the company, the entire tools budget is just a cost center. Identifying as a "tool person" at all just means that you're climbing a greasy pole. This is true even in "pure" software companies -- the difference between working on a business-critical initiative and, say, code-review tooling, can be everything to your career path.
Just to emphasize this point, consider the growth paths for the other careers you mentioned. Lawyers get paid well overall, but making partner depends on bringing in business. Surgeons and doctors are a bit more complex due to licensing scarcity, but if you know anyone in private practice, it's the same gig: get clients, grow the business. Meet the minimum threshold for technical competency, and nobody really cares if you're the best surgeon in the state, so long as you're bringing in patients.
The world revolves around money. Software is relevant only to the extent that it makes money.
Even there, you kinda feel the org's Eye of Sauron looking at you wondering why you haven't ascended into the clergy of management sometimes.