I am not quite sure what your argument is. That there is a segmented labor market and some jobs are shittier and other? I do not think that it has ever been a bone of contention, especially on this list.
That shitty jobs are a necessary product of "capitalism." Well, it depends what you mean by "capitalism" - the Canadian or European varieties are decidedly less shitty its US counterpart. In fact, I would consider it a smashing success of the Left if the US became more like Canada or Western Europe.
That people are trapped in shitty jobs against their will? Again, it depends what you understand by "will." Some people do not mind working in off or low paying jobs with no prospect for career advancement (a definition of the secondary labor market) - which I believe was the point of the story of your youth you posted earlier. I certainly have no problem with people living simply and renouncing the "rat race" - so if that is a choice, why arguing that they are trapped there against their own will by the system?
Please also note that lumenproletariat, aka the "trailer trash" is not limited to the US or capitalist economy in general. The species was also well established in the socialist economies of Eastern Europe, which you could not justifiably accuse of creating barriers to education or employment.
As far as your comments about the people who join the service, I knew a number of them and many of them were my friends. I may add that this crowd generally compared favorably to, say, undergrads whom I taught at Rutgers. Most service people I met were not blood thirsty monsters. Au contraire, they were quite reluctant to go to any war - more so that most civilians since _their_ asses were in the firing line.
I may also add that I have no objection to people who actually join the service, albeit it is not an option that I would choose. My beef is with the bar, NASCAR and bumper sticker warriors who cheerlead the slaughter while keeping their fat asses safe in their Hummers and SUVs. I think they are scum.
My other beef is with a certain genre of narratives manufactured in large quantities by the left, that either romanticizes the lumpenproletariat and poverty in general or elicits pity for them (Jonathan Kozol is one example than comes to mind). My main objections to this genre is that it is often disingenuous - it is either to produce proper 'workerist' or 'populist' credentials for the manufactures of the genre themselves, or to produce exotic experiences tainted with the dashes of guilt and compassion for the bored, guilt tripping middle class audiences.
Wojtek