That doesn't work, because you'd need to agree to a training reimbursement if you break your contract early when you sign your employment contract on hiring.

So if the company isn't willing to pay you "competitive wages", why would you agree? You wouldn't.

The real reason this is happening is that desirable employers are refusing to hire people without experience, so entry levels are forced to go to "undesirable" employers to get training, then promptly dump them and get a "better" job the minute they have enough experience. The employers who are getting used and exploited need to try to stop this exploitation and reduce turnover, so they very fairly say "your employment contract is X months, and we will eat the cost to train you if you complete your contract, but if you leave early, you need to partially reimburse us based on how long you stayed". It's not about "punishment", it's about the employer not being taken advantage of.