I worked on a farm throughout my Uni course, later progressing to a full time job as a manager on a local horticultural site for 2 years. After this I spent a year on an arable farm before leaving the sector altogether.
I paid for a lot of my own training in order to find a job and whilst I enjoyed the work in parts I ultimately left because as a career it demands far too much whilst offering comparitively little in return.
I was unfortunate enough to work for a few farmers who were absolute $%£#'s, but regardless of that I suffered low wages, was expected to priortise the farm every weekend from Feb - late Oct, restrictions on holiday and poor working conditions. Nowdays I take home double the wage for half the hours, I haven't worked a weekend in 3 years, can take a summer holiday with my partner and I'm home relaxing by 1800 most nights.
I guess for a young person looking at that they see poor wages, an enourmous strain on relationships and no recreation time (I couldn't enjoy my favourite pastimes of golf and cricket were I still on the farm) and its easy to draw the conclusion that no-one would want to enter the sector.
I never quite understood the attitude of the Harper students etc who seemed to be proud of working 100+ hours... my old man always said that no-one goes to their grave wishing they'd spent more time at work, and surely at that age life is for living.
Anyway just my 2p worth and I'm sure there are people who feel differently, but I just wanted to outline why I think so few YP are interested in farming unless you come from a farming background.