Probably has a lot to do with social media and how everyone online is telling young people not to go into teaching because it's such a horrible job.
By the way in case you didn't notice all jobs are experiencing difficulty hiring. Not just teachers.
Could be, and that would account for the lower new hire numbers to the profession. With that said, the social media theory doesn't really fly for the mass exodus of the veteran teachers leaving the profession. As one of those veteran teachers / coaches, from my perspective, the reasons seem to be because of the lack of accountability from within the home, more commonly a single parent home. The lack of fathers involved in the home have become astronomical, and although I can't put it all on that, it is by far one of the top reasons there are so many "mental" and discipline issues. To equal that, weak administration that give into parents that are focused on their own selfish personal agendas. Sadly, the strong administration are handcuffed by government policies and procedures that are just atrocious. Lastly, God has been taken out of our school's. Personally, I feel that this is the number one issue. It isn't hard to draw a line between the decline of the classroom from the time we had God in our schools to the point we are now, where God has been cast out of our classrooms.
Sure, other jobs are experiencing hiring issues, but none of those jobs are more important than those who invest in educating our youth. Without proper education, the job issue will only get worse.