There has been a lot of debate about what being drafted might cost a draftee, and how much it might cost in training that is not used for a long career.
The implication is the volunteers stay on a long time and are paying back a larger return on the training investment. This is true for pilots and for certain skills which have entrance requirements and have service commitments to be “paid” by the soldier receiving the training.
Training pay back is not that much of an issue with the combat arms skills. Retention there is becoming an issue.
So, if you discount the difference in training between a drafted force and an all volunteer force you should look at some of the cost of not using a draft.
It is expensive to lower your educational and aptitude standards, many things cost more from extra training failures, to writing technical instructions at the 8th grade reading level, to extensive remedial training and low retention rates all argue against the idea that it would be more costly to have a percent of the Army as draftees.
There are also added costs of designing things to be simpler to use for the lower aptitude volunteers. We also begin to trade expensive design approaches with more development and support costs as well as contractors in the operational areas because of the aptitude drop of the all volunteer force.
Contractor support also covers up for the manning limits at greater cost in many cases than doing the job with soldiers, particularly where there is eminent danger from combat operations.
In the period since the draft ended equipment support costs have risen faster than military personnel costs for a much smaller force. It is not all aging equipment or operations tempo.
We see more functions done by software, expensive, unreliable and hard to maintain software instead of using skilled skilled military personnel who are hard to recruit.
Finally, there is the moral issue. The services have had to lower their standards for character and psychiatric issues to meet recruiting needs, these standards would remain high with a draft supplemented force.
There are more moral arguments, those being the draftees comes in with a critical eye, not wanting to be there they want the thing over fast, desiring to go back to being tax payers they want it over cheap and they criticize the same old processes (SOP’s) and demand improvements in efficiency which career soldiers may over look so as not to rock the boat.
In my quick view; a higher caliber soldier and a little rocking the boat make strong arguments for the draft.