I think we can acknowledge this without feeling like we're 'bad-mouthing' teachers at all. Depending on the grade level, content knowledge and expertise is only one part of a good teacher's skill set.

Salaries are unequal, so that naturally reduces the prestige of being a teacher. It's also a traditional "feminine" job with strong parenting/caregiving elements that further chips away at its status for some.

I don't judge anyone for seeing teaching as a "plan B"; however, the significant turn over/drop out rate of teachers would call into doubt whether it is as safe + easy a back up career as we culturally project.