“Tailgunner” Joe seems to have been every bit the stereotypical politician. You could tell he was lying because his lips moved. I’d have to get a second source to confirm it if he claimed he was a US Senator.
FWIW, I can’t attest to how things were in the past. But as far as the present day Army:
Drill instructors are not allowed to use curse words. - TRUE
They are no longer allowed to beat recruits physically. - TRUE
Anyone who does these things will be punished by the higher ups. - So very TRUE
There is no more tolerance for hazing from fellow recruits. - Higher ups do not police recruits, they police drill sergeants. The drill sergeants police recruits. Because of that, I would say there is more tolerance for recruit-on-recruit hazing than any abuse/punishment given by drill sergeants.
There was a tv show that answered the OP’s question directly. It was called “Sarge” and was on the History Channel several years ago. It was an exploration of the role of the NCO throughout history. In one segment they were talking about Boot Camp. A current Marine DI spoke about how they were trained to break down a civilian using psychology and physical training in order to build them back into Marines. Then it switched to R. Lee Ermy who said (paraphrasing) “I was a DI at the height of the Viet Nam war. They doubled the size of the recruit classes and shortened the training time. We didn’t have time to deal with problem recruits. When they stepped out of line we beat the shit out of them. Most were going straight to combat. We were trying to save their lives.”
FWIW my father was Parris Island Class of 45 and I watched FMJ with him. He was amazed at how accurate the Boot Camp scenes were.
I went to Army Basic Training in 1989. There was cursing but not as pervasive as the movie. Lots of PT for corrective action (my platoon once did 600 side straddle hops in a row. That equals 1200 jumping jacks. Oh to be young and in shape). No hitting or other physical contact. One of the Drills had a memorable technique. When one of the privates pissed him off he would make him remove his helmet. The Drill would then beat the crap out of the helmet with his clipboard all the while lamenting the fact he could hit recruits.
I don’t remember being told it was voluntary, I just reasoned it could not be mandatory. Same with when they tried to make me attend religious services, but that is another story.
“…couldn’t hit recruits.” Stupid little phone big thumbs grumble grumble.
EB Hammer in With The Old Breed describes Marine bootcamp in WW2, he doesn’t dwell on the brutality but says they realized in combat that everything they had experienced in training was to keep them alive.
In Currahee! Donald Burgett devotes half his book to Airborne training for the jump into Normandy. Great book, physically demanding and brutal training but the guys undergoing were just about as badass as it gets.
Colonel Hackworth in About Face tells why he was always so physically brutal to the men who served under him.
These 3 books ought to be required reading for everybody, 3 smart guys telling the truth about war.