That does not necessarily follow. It’s very difficult to put food on the table while going to school in hopes of landing a job in a new field.

Pay living wages and provide paid, on-the-job training. That will get prospective employees through the door.

If it's that important to employers, they'll pay them during the training period.

This used to be standard practice. It's a modern development (80s on) that businesses demanded workers come pre trained.

It does at a high enough salary. Some people are unable to pay for their own training but you don’t need everyone you simply need enough people. Start offering Doctor money and people will jump through insane hoops, but it scales down so even 20$ an hour will motivate some people to do a specialized training course on their own dime.