Presumably the "calling" is the aspect that has been abused in order to underpay teachers. In my experience they are underpaid across the board but particularly

Presumably the "calling" is the aspect that has been abused in order to underpay teachers. In my experience they are underpaid across the board but particularly in public sector roles (at least in the UK). What's interesting, and isn't something the article covers, is that demand side at the high end is nearly insatiable. Private schools in London consistently increase fees well above inflation year after year and never fail to fill places. The teachers there do okay but it's hardly stellar pay and although many of the schools discourage teachers tutoring it's commonly the way that income is boosted.