It's true that they tried to constript many people from the poor regions or the regions where most of the people are the ethnic minorities. Although, people from the major cities, including Moscow and St. Petersburg, were and are still conscripted in large quantities since September. It is just men from the major cities are more likely to be educated and informed, so it is harder for the military offices to find them and force them to join the army. For example, one official accidentally said that the plan for the mobilization in Moscow was not even half completed.