Only successful people can afford a CV of failure

"I’ve had much luck in my life: being born into a middle-class family and having any natural ability nurtured by my parents and then by the education system"

This might be lucky on the part of the individual, but parents that sacrifice their own time, money, and life for their child's future definitely isn't luck. It's a choice. If more people saw it this way, we might have parents that actually cared about their child's education and less people in abject poverty.

..and 'nurtured by the education system' is kind of a joke in the US. The K-12 education system is terrible for everyone.

"Yet there is a dearth of thinking about how we can make these jobs more fulfilling, better paid and more respected"

The problem is that low-skilled jobs will always be low-paid in a capitalist system because pretty much anyone can do them. The only way to counter this is to artificially limit the amount of people that can actually do the job by limiting the supply or create some sort of union to force higher wages. Both bad ideas for the long-term.

"and to increase the relationship between effort and success."

Effort has never equaled success. You might put all the effort in the world into something and it you will still fail. You can always learn from your failures. I failed job interviews, businesses, and many other things before I succeeded. We should be stressing to our youth that you aren't entitled to success. You need to earn it.

"it is not uncommon to find graduates working in a bar on a zero hours contract"

What was their major? STEM majors have little problems finding work. Liberal arts? many can't find a job. We should be encouraging students to pick a major that at least has chance of being able to get a job that pays well enough to pay off their debt. Otherwise, it's just a gamble. They might as well start their own business and skip college altogether.

We should be talking about the trades. I know people that are carpenters and electricians and they can't get enough young people even interested enough to apply for the job.

Mostly because they don't want to start out from the bottom and work their way up. Many feel like they should be making $100K right away.