In order to escape, these young people have to risk the crocs to get into South Africa where they risk being sent home to be bruatally punished.
Unlike the "war veterans" who are young party cadre, thugs pretending to be engaged in a "Third Chimurenga" or "hondo yenzara", the Green Bombers are draftees into a vile form of National Service. (the "second Chimurenga" ended in 1980 with Mugabe taking power. Most of the "war veterans are in their late teens or early twenties)
Note that the "war veterans" are not leaving Zim. They are the people who mounted the farm invasions and who are equivalent to Hitler's SturmAbteilung.
The Green Bombers who take a liking to what they are initially forced to do will becone indistinguishable from the "war veterans".
If the "war veterans" had any appreciation for history, they would realize that the sturmabteilung eventually became inconvenient to Hitler and had become individually too dangerous to survive, so they were purged by a more effective set of monsters, the SchutzStaffel. Perhaps if Mugabe continues to thrive the "war veterans" might find themselves pruged by a new organization, perhaps recruited from soldiers returned from the DRC campaign.