The United States can only arrest people who are guilty of crimes. The Soviet Union can arrest anybody it can get its hands on, without regard to innocence or degrees of guilt (think the Brittney Griner case where she may have technically been guilty of the most minor offense). This means that Russia and other tyrannies can take hostages whenever they choose to and use them as bargaining chips. We cannot do that.  

Consider the recent trade. Russia freed journalists who were simply doing their job. Germany freed an assassin who had murdered a political dissident in cold blood. It was anything but a fair trade, but as National Security Advisor Jake Sullivan said, “They hold the keys.”

They not only hold the keys, they also decide whom the keys will be used to lock up. There is little that democracies can do to prevent tyrannies from creating bargaining chips that can then be used to free guilty murderers and other criminals. Yet as Sullivan also said, it is difficult to resist the moral and emotional desires of family members to see their innocent loved ones back home.