The standard of many school leavers is abysmal. When I was an employer, some of the job applications I received would make you weep.
Still, as there were so many applicants, it made the primary sorting of applicants easy, and it usually resulted in about 50% of them receiving a 'Thanks but no thanks' letter by return of post.
They should not be allowed to leave school until such times as they achieve basic literacy at the least.
G