I most places I worked in (all in Europe), Junior Devs are generally hired as an investment, since their productivity sucks until they become more experienced so the idea is to teach them until they become more senior.

Yes. Same here. I never would have managed to build teams as large as I have if I didn't create some of my senior devs out of junior devs.

You can't really replace such Junior Devs with LLMs because the LLMs don't learn (at best they'll somewhat follow past guidelines still in their context until those guidelines are push out as the context fills over time).

Yes. Exactly! It boggles my mind when folks talk about all the money they're saving on junior devs. A forever-junior sounds terrible, to me - no matter how cheap.

Maybe in the US (were job security is a joke) there's more a tendency to hire Junior Devs as cheap manpower.

Yes. When I was doing consulting gigs for clients too incompetent to maintain their own developer teams, I would hire junior devs and charge clients for their work. Organizations too incompetent to hire and retain their own developers are also pretty reliably too incompetent to tell the difference.

Even so - while I never felt I owed those (generally sociopathic, often malicious and usually willfully stupid) clients too much loyalty - professional ethics still meant that I didn't saddle them with any fully un-supervised junior developers. So they were still better off with my consulting team than with an AI.