Both Docker and Jetbrains are working on software projects just like the rest of us. There is still boring shit work to do that no one else wants to do, so they

Both Docker and Jetbrains are working on software projects just like the rest of us. There is still boring shit work to do that no one else wants to do, so they need junior devs to shovel it off to. So yes, they have juniors, mid-levels, and everything up to staff and beyond. They are no different than any other company. The difference is probably that it is harder to get those jobs because everyone wants to work for the flashy exciting companies. I was considered for a job at Docker a long time ago (when I was an early-midlevel) and the recruiter told me that over 1,200 people applied in 5 days. For entry-level/intern positions I assume it is similar or even worse.