Im not gonna argue your theory that "broken lug bolts are from loose wheels cuz I think your right...the lub bolts do break as a result of the wobble torque exerted by the wheel as it moves on the hub after coming loose....BUT....loose wheels are often caused by over tightening rather than under tightening.
I am glad you commented. It gives me a chance to provide more detailed information. Your insight is not actually correct. That is exactly why I could not let Degen's post stand.
I worked with Transport Canada for quite a while when I was responsible for vehicle safety at my employer. I can, assure you that the regulation was developed at industries request. Industry doesn't like fatalities any more than Transport Canada does.
The first thing to understand is that wheels flex with load changes as they roll down the road. As a result they experience millions of load cycles. When the stud is properly torqued ABOVE the normal tension stress load, but below its tensile strength, the stud does not lengthen or shorten. It simply holds the wheel on and the stress changes do not "work" the stud. If the stud is overtightened, it almost always snaps when tightened and does not fail on the road. It does take a gorilla to get the nuts or studs off though.
The problem with undertightening (which is not the same as loose at all) is that the load cycles can cycle the actual length of the stud whenever its working load exceeds its clamping load. This works the stud over the course of millions of cycles and causes it to fail in fatigue over time.
A loose stud will usually be obvious because the wheel starts flopping around and makes a loud racket. Most drivers notice it long before the nuts or studs fail. This is NOT the more common fatigue failure mode.
The problem with fatigue failures is that the wheel is not loose. It is tight, but not tight enough. So there is no flopping around or wheel noise and the driver does not know it's happening until its too late.
As Transport Canada noted, it is very important to tighten wheel studs to the recommended torque and the reason is to avoid fatigue failure in a stud that is tight, but not tight enough.
Wheel studs are a Goldilocks situation. They shouldn't be too tight or not tight enough. They must be just right. It's very hard to do that without a torque wrench.
That already takes too much away from
@David_R8's thread so the fatigue issue has been moved to its own new thread here where we can discuss it to our hearts content.
Edited - Anyone wanting more info should feel free to do their own research or contact me by PM or post in this new thread. I can provide as much detail on the relevant engineering theory and material science as anyone might so desire.