The military had the same problem, and first tried to deal with it by lowering standards, which was a mess and reduced military readiness.
So they came up with a better way of doing business: delay new recruits for some months, while offering them the equivalent of a “physical prep school” to achieve physical standards. This works in several ways.
To start with, there are recruits who are just unmotivated and/or in bad physical condition. Even with a few months of lead time they either can’t, or won’t, physically improve themselves enough to pass standards. And this can cover the gamut to include abnormal weight, lack of strength and stamina, and health problems.
But there are many recruits of both sexes who are physically fit enough to pass but not to do well, and this prep time strongly raises the standards of recruits.
If they wash out of this very relaxed training, they would have never made it through real training. But the emphasis is not to wash them out, but to get them up to standards.
Importantly, training is not co-ed, so female recruits have female trainers who can perform to standards, plus they have far less sympathy for female recruits who slack off and make the other females look bad.
This prep training is also individual oriented, because new recruits have such different needs in getting prepared. A recruit who is physically a mess at the start but is almost up to standards because they are very motivated will be a better performer than one who just passes but makes no effort to do any more than just pass.
Recruits (police, military, whatever) who are coddled and babied at the outset to get them up to minimal training input standards, will be the first to quit when it gets tough in real life on the job.
Opinion of a former Navy frogman.