Apprenticeship Schemes. Historically an “apprentice“ was employed by a tradesman on low wages and learned the “trade” over a number of years. This was usually in conjunction with college training or day release training, some apprentices still follow a similar course but nowhere near enough.
The change came some years ago when 18 yrs became the school leaving age. Vocational students - about 50% of leavers had to decide wether find work or continue college training.
The brightest, that might have become electricians, plumbers and other skilled trades were encouraged to go to University to get more qualifications. At 21 most enter the job market expecting an adult wage but most have had poor quality training, little work experience and no employment record.
There is plenty of skilled work available, it is mostly being done by migrant workers, if migrant workers were not available employers would have to train apprentices, it’s fairly easy to compel employers to train UK workers, a number do already. What is more difficult is to encourage trainees to commit to learning a skilled trade at 18, the present system is not going to change anything.