If this guy showed up at Australia's border with no return flight, incorrect visa and everything else he screwed up, I'd wager he'd have the same experience.
I'm Australian, so I see where you are coming from.
Living here in Canada, so close to the border with the USA, it's totally different. It's so close and easy, I drive to Alaska twice a month in the summer just to get good Thai food.
And from my own experience I can tell you this - he may have been denied entry to Aus or at least had a few issues, but I'll bet my bottom dollar he wouldn't have been belittled and made to feel like the scum of the earth for hours and hours.
I don't see what distance has to do with it. You're still crossing the border from one country to another regardless if you live 5 minutes or 5 hours from the border. To be honest, his experience is not so bad. In pre-EU Europe (and probably even now with some non-EU countries, but I can't say since I haven't tried) this kind of behaviour was often par for the course, and many times worse when trying to leave your home country for any reason during communism.
"3 to 4 months" according to the original article - I don't know what the usual thing to allow casual visits by Canadians to the US is, but I travel there from Australia fairly regularly for vacation and visiting family and friends under the visa waiver program, and I know I'm limited to 90 days - if I want to stay longer than that I need to get a visa.
Nah, that's totally not true. My Italian friend came over for a month or so to visit his girlfriend, was a bit evasive for some reason for some questions, and got some pretty bad treatment.
As someone else noted, it's a technique they use to try and unsettle you. Not that I necessarily agree with it, or like it, but at least there is a reason for it.
The biggest thing that raises red flags is that he said "I left my job so its no issue about the time off".
No return flight AND "training" with no documentation to prove that (phone number of admin office to confirm, length of training, how much it costs etc.) is a slam dunk for people who are going to work illegally.
Do your homework, be a smart traveler!