A lot of factors influence the likelihood of getting hired. Among them are the amount of jobs available for every applicant, what companies are looking for and the individual searching for the job.
Not every position posted is filled. In some cases, companies post jobs to gain candidates for a new job opening. Changes within the company can remove the need for the position. There are times when the company posts a job opening, but instead of hiring a new employee, it promotes a current employee to the position.
Some companies have unrealistic expectations for applicants for open positions. They look for a perfect fit for their job. Finding someone who is perfect for the position that is posted is rare. In most cases, the sort of person who is a perfect fit wants a better job to gain new skills.
Sometimes, the field that people train in have very few jobs available, making it hard to land a position. Many jobs are available in truck driving and oil field work, for example. Training is available in these fields, but it takes time to prepare for a position.
To increase the likelihood of getting a position, explain why you are a good candidate for the job. Talk to the hiring manager, if possible. Recruiters are more focused on rejecting candidates instead of hiring.