But you can domestically hire that junior too - I am just arguing about that pure replacement model. You can pick the top talent from juniors too. Otherwise, if nobody ever hire juniors, at some point you run out of any workers because there is a portion for their life when they simply cannot get the job in their field. Young people won't invest the field if the first job requires that you are magician or have 10+ years of work experience that you either can't have or need to use your free-time.

Anyway, big tech doesn't work as an generic example because they have much more resources and therefore it cannot be generalized.

US also is an exception because the only expectation is English language. In other countries you may need two languages.