To me this is less a millennial problem and more a recruitment or cost/benefit problem. You can't hire any random unqualified person and expect them to be super productive in a hard physical job and have stellar work ethic. This is where an interview, CVs, and references comes in. The fact that the "good" employees were whisked away highlights that the issue is pay and/or recruitment not birth date or nationality.
Another issue is that not everyone is willing to work a hard physical job or lots of hours for incremental additional pay. For instance, I would not work an additional 4 hours per day even If you paid me 75% more.
Finally, the employer is trying to pay their employees as little as they can get away with. The corollary is that the employee will (or should) try to work as little as they can get away with. That is just the outcome that you get in the system that we are in.
Wow. Would it be fair to say that you are highly educated, well compensated, and have no real familiarity with uneducated, working class folks? First, in the instance I reference, there is no random anything. As the hiring manager, my son has little interesting in wasting his time, and a great deal of pre-placement training and safety certification expense, by "Randomly hiring unqualified persons". Your assumption that there is no interview, review of references, or attempt at extracting a resume from somebody who has no idea WTF a "CV" is, is way off base. Try to get your head around a group of applicants who could only hope to generate a resume if they sat down with a career counselor at a government unemployment office, AND may very well be the first person in their family to ever have needed one. For most of these folks (and yes, I AM one, working class, no post secondary ed.) the closest they will ever get to a "resume" is filling out the column marked "previous job history" on a preprinted application that was torn off of a pad full of them. The fact that good laborers, with a long work history in this specific industry, get to name their price means nothing other than they are an anomaly. These were guys who not only had verifiable experience, but had relocated to better themselves, which is rare. They have nothing in common with those "short timers" who bailed to return to mom's basement, or grovel for their job back at the auto parts store, making 1/2 as much, since working moderately hard, or in unpleasant conditions, is not "what they expected"
As for not being willing to work long, or hard, how does it work in your world, for those with no experience, no skill set, no training, and no post secondary education? I know many, many guys who are everything from highly paid execs. in the construction industry, to company owners, who started at the bottom. Shit hours, shit conditions, and a broom in their hand. I guess I would have to add myself to this list of success stories, the list of guys who started at the bottom and didn't value being a quitter as much as you do. When your are in my son's position, and you have seen a new employee perform for a year or two, being reliable, dependable and willing to be a team player, you know the answer when that guy approaches you and says, "I hear you are looking for equipment operators, how do I move up, and stay with this company". You do what it takes to keep him, and get him trained to climb the ladder. That's how the world works outside of degrees, certifications, linkedin profiles, job coaches, head hunters, and multiple interviews before being offered a position.
Your final comment is ironic. Once value my kid's company has is, "we pay better than average, and expect better than average". In this case, they start unskilled laborers at 25% higher than competitors. They also walk away from jobs where their customers want them to cut costs, and the only way to do it is to battle with competitors that use minimum wage employees, or even undocumented workers. They don't want the bottom of the barrel on high risk job sites, wearing their company uniforms. Other companies wouldn't hesitate to hire monkeys, if they could make it work, and pay them a few bucks less. I'm not sure where your head is at when it comes to what unskilled, uneducated and untrained new hires are worth, out there in fly-over country, but there are millions of men and women that would kill to make $16/HR with great health care and tons of overtime, if it was offered. The median family income in the region we are discussing is $43.4K a year. So with no college education, no trade skill training, and no prior experience, you could end up making the median family income for the area, working four 12 hour shifts a week. Yet it is a constant battle to find and retain qualified entry level help.
As you clearly state, this is an obvious case of an employer paying as little as possible, and as a result, when given that chance, the employee should try to do as little as possible to "stick it to the man". I gotta' give you credit here, you sure see the world a bit differently than I do. But then, I started at the bottom, never got a degree, operated two companies I founded, retired 15-20 years before my peers, and have more than I'll ever need, so don't ask me.