I've been reading some of Eric Hobsbawm's work on 'social bandits,' but also a lot of criticisms of the idea. It seems like a lot of recent academic work sees the concept of the social bandit as overly romanticized and as one which does not stand up to close empirical analysis. So are there any... bandit scholars here?
What were the actual MO of bandit groups like, in reality and not in folklore? What sort of illegal / semi-legal activity did they engage in? Who were their victims and why? Who harbored them and why? What overtly political agenda, if any, did they espouse? Let's limit the discussion to relatively modern times say 18th-20th century where hard evidence is easier to come by.
Also it seems like bandit groups fluctuated wildly in size. How did part-time bandits live?
Finally a lot of the work I've read largely dismisses the bandit group as a relic of times past, suppressed by the growing power of the state, but aren't, say, drug cartels, a continuation of the tradition? Can Pablo Escobar be seen as a sort of social bandit (in folk memory if not in fact) ?
As a disclaimer, I'll mention that I haven't read anything specifically dedicated to banditry, but the subject has come up quite a bit when reading about the late Qing. This doesn't answer all your questions, but it can shine some light on the topic.
Bandits usually thrive when the state isn't able to enforce its will; a common place for bands to form is in less-developed warzones. During the Taiping Rebellion, the deadliest civil war in history, the line between soldier, civilian, rebel, and bandit blurred, and it was common for soldiers on both sides to desert and for bandits to join sides with whoever seemed to be winning at the time; they usually weren't quite committed to banditry as such, just to making money, so they often made up each side's periphery soldiers, who could be used to take hold of areas where enemy troops weren't present in force.
During turbulent times like that, the opposing governments often weren't able to adequately pay or even supply their troops, which meant that soldiers often had to take whatever they could find from local civilians; in the book What Remains, Tobie Meyer-Fong mentions how opportunistic the combatants were. There were several instances where a town or county's local militia would join the rebels, and then switch sides over to the Empire once they gained an edge. There were incidents where bandits would steal uniforms to 'officially' requisition funds from pawn shops, and where they would waylay refugees for valuables, then tie them to trees and burn them when they failed to produce anything.