Several reasons for that. 1. The American legal system is now such it would be litigated to death. 2.The battles about females entering the draft would be epic, but ultimately a no go. 3.The general physical fitness of the draft age is pathetic. 4. The people in the past most in favor of the draft would now be the leading opponents (the political right)
Take a step back and imagine the instituion of a draft in 2023. It would be comical to watch.