This is why I said "even if it takes them a while to land a job". The point is they can apply for job after job after job after job for years (as in, literally years) and still get a job before a graduate.
I accept that for any one single job, if a grad is struggling to get it, a GCSE bod will struggle even more. So it's like, say for a job, the grad has a 5% chance of getting it and the GCSE person has a 2% chance. But the GCSE person will be applying for jobs for 5 years before the graduate does (maybe slightly less if you consider the milkround). They will have literally applied to thousands of jobs before the undergraduate graduates. Sooner or later they will luck out, get a job and then start compounding that experience. This may well be a crap job flipping burgers. But then they still have years ahead of them, so they move on to another position and gain more experience. And still the undergraduate is at uni.
They have so much time on their side that if they are driven, showing good enthusiam, and smart (they must be reasonably smart if going to uni was an option they could have taken) then they will land a job inside a few years.
Obviously there's a chance the graduate, when they eventually get a job may end up on a higher rung. But not necessarily, I didn't, and these people going into accountancy at 18 seem to have done quite well for themselves.