Ask HN: Why Will No One Hire Jr. Devs?

I'm graduating from a developer bootcamp in Portland, OR next month. I have extensive startup experience in non-developer roles. As I'm pounding the pavement looking for my first jr. developer gig, I'm finding many companies are turning their backs on jr. developer candidates without reviewing work / resumes / etc at all. It seems like a lot of people are excited about training jr. devs, but not excited about hiring them. Does anyone have any tips for a new jr. dev out in the wild? Why are companies reluctant to hire jrs?