The reason was bigotry, which is why problems like these were a kind of 'secret' method with plausible deniability. Otherwise why not just declare it as an open

The reason was bigotry, which is why problems like these were a kind of 'secret' method with plausible deniability. Otherwise why not just declare it as an open policy? People were not 'likely' to emigrate, emigration out of the USSR was exceptionally difficult and impossible for most.