Mobility of the subjects is always a sore point with totalitarians. The idea that a citizen can just jump on a plane and go somewhere or get in a car or ride a bus without registering destination and waypoints with the Authorities and can do it without the leave of an 0ffice is horrifying to leftists of all apparent stripes. Mrs Bill signaled her thoughts on that pretty strongly with her “Hillarycare” attempt back in the 90s. One facet was that if you wish to maintain your “coverage” when you travel outside of your designated Zone you have to register with a Federal Office that could deny your application to maintain that coverage.
It was the Right of Departure that was the last defense of the downtrodden serf against his oppressors.