Someone with an “undeveloped prefrontal cortex”, a vague and insulting description, would be a liability on a battlefield. Not every soldier needs to have a genius IQ, but they need to be competent for their role. The military is also not a college financing program and only an fool would treat it like one.
What I'm getting at is that it's ridiculous to try to argue that a 17-18 year old's abilities to plan and make decisions around the future are on par with the abilities of a 25+ year old. The average age of enlistment is 20-21 with a lower bounds of 17.
I'm not arguing that the military doesn't provide _lots_ of opportunities to people or that people only enlist for the benefits (the best I could find was a RAND Corp survey predicting likelihood of choosing enlisting of working or going to college), I'm arguing that it's shameful that we aren't able to provide similar opportunities without putting young people, who are at a disadvantage when calculating the risk involved, in shitty situations.
Another way to look at this is that if you are young, you only have until the age of 25 until your brain deteriorates to the point that you are incapable of taking real risks.
It's disappointing that as a society we seem to be cool with (mostly poor) people with undeveloped prefrontal cortices having to make a choice between incurring significant high interest debt (which they were probably never given the tools to make informed decisions about in the first place) or risking their lives for something that's free or at least attainable in the rest of the developed world.