System Countries are safer. The population is better fed, social infrastructure is largely repaired, crime is almost nonexistent. The chance that someone is picked is relatively low. Some are willing to risk that kind of outcome for the long term benefits that the System provides.

Non-System Counties aren't as well recovered from the famine. Rationing, dictators, bandit lords, and slavery are common. They aren't entirely lawless but because they refuse to join the System, their food supply remains limited.

Not every non-system country is like this though. Some are normal and well fun but it wouldn't take much to destablise then