I know I'm going to get shot down for this, but as a person who works in sixth form, we don't "kick people out" for our own benefit. People who work in education generally care about their students very much. We want what's best for them. A student who is struggling to achieve at AS or the end of Yr 12 is highly unlikely to suddenly start to during Yr 13. Especially with the new, more difficult A-levels. Most post 18 providers care about grades, not subjects or qualifications. Therefore the vast majority of students who are struggling at the end of year 12 (that's is struggling to gain at least three E grades) would be better off starting again, either with different courses or subjects. You can study at Russell group universities with Btecs and diplomas. A-levels aren't necessary. They're simple one way of getting there. Low A-level grades will open fewer doors than higher grades in other courses. What's one extra year of study in the whole grand scheme of things if it means you have more life choices later in?!
Ultimately it hurts schools to turn students away. We get massive amounts of funding for post 16 students, for each one who doesn't complete A-levels we lose funding for them, we don't let them go lightly. I work my backside off to keep kids in over the year and to work with them on careers advice and support.
www.gov.uk/guidance/16-to-19-funding-how-it-works#how-the-funding-formula-works
We are also required to publish our sixth form retention rates. The dfes automatically does this for us.
www.gov.uk/guidance/what-academies-free-schools-and-colleges-should-publish-online
I know this is long, but sometimes I resent being lumped in a pot that suggests schools and teachers have it in for weaker students. I love my kids and my job (no matter how much stress caused) and I don't let them down if I can help it!
I don't agree with the school in the Guardian though btw!