1. Centrally Planned Economy:

The USSR operated under a centrally planned economy where the state controlled all aspects of production, distribution, and labor allocation. *
Labor needs were primarily met through internal mechanisms like state-directed job assignments, vocational training programs, and population transfer policies within the Soviet republics.
Mass immigration of foreign workers wasn't necessary to fulfill labor demands as the state had direct control over its internal labor force.

2. Ideological Focus on Nationalities within the Union:

The Soviet Union was a union of various socialist republics, each with its own distinct ethnic and cultural identity.
While promoting unity and Soviet identity, the system also recognized and, to some extent, maintained these distinct national identities within the republics. *
The focus was more on managing the movement and integration of different nationalities within the USSR rather than large-scale immigration from outside.

3. Strict Border Controls and Emigration Restrictions:

The USSR had very strict border controls and heavily restricted both emigration of its citizens and immigration of foreigners.
This was partly due to security concerns, ideological differences with capitalist countries, and a desire to prevent brain drain.
The emphasis was on self-reliance and utilizing the internal population for economic development.

4. Concerns about Social and Cultural Integration:

Large-scale immigration could have posed challenges to the existing social and cultural fabric within the Soviet republics, each with its own languages, traditions, and demographics.
The centrally planned system aimed for a degree of social cohesion and control, which might have been complicated by mass immigration from diverse backgrounds.

5. Focus on Autarky (Economic Self-Sufficiency):

The Soviet economic model, particularly during certain periods, leaned towards autarky, aiming for economic independence and reducing reliance on the external world. *

This reduced the perceived need for foreign labor or expertise through mass immigration.