What I would like to know is how almost every president since Eisenhower has been able to deport millions of illegal aliens without millions of trials but Donald Trump cannot do so.
There are no trials. There is a hearing before an Article II Immigration Judge, formerly known as a hearing officer. A hearing does not take months or years.
For aliens detained at or near the border upon illegal entry, they may be processed without the hearing.
Are Article II Immigration judges subject to A&C?
Or can the Executive just start appointing a couple-hundred of them?
In several instances, the Executive has been their own worst enemy. By forgoing hearings via Article II Judges, they often push adjudication right away into the Article III judicial realm where habeas petitions are sure to follow.