People cannot freely migrate between the new republics due to linguistic and ethnic barriers as well as political borders.
There were no or very few linguistic issues to begin with, and people could migrate easily, for a while, until the internal and external tensions grew, which happened in most cases within a few years. But yes, the experiment is not as clean as one would hope for. Still, being able to experimentally test political and social ideas is a luxury, and this is one of them.
There was almost no private housing in the soviet cities, and to move to another city you needed government authorization. After the collapse of the USSR there was a huge unemployment, and finding a job in the new place was nearly impossible. Ethnic tensions were also extremely high.
There were no or very few linguistic issues to begin with, and people could migrate easily, for a while, until the internal and external tensions grew, which happened in most cases within a few years. But yes, the experiment is not as clean as one would hope for. Still, being able to experimentally test political and social ideas is a luxury, and this is one of them.
There was almost no private housing in the soviet cities, and to move to another city you needed government authorization. After the collapse of the USSR there was a huge unemployment, and finding a job in the new place was nearly impossible. Ethnic tensions were also extremely high.