Yes. In each example given no mechanical locking is typically used. The fasteners maintain their torque only via their stretch, which functions like a spring washer.
Loss of torque in caliper bolts can lead to catastrophic failure of the system. Were the system to fail, and injury or property damage resulted, a design defect lawsuit between the injured party and the vehicle manufacturer would very quickly include the repair shop. In that moment, the repair shop must be able to say they replaced the system components with suitable parts in accordance with the factory manuals. In short, if you are aren't torquing fasteners in your shop, you are taking shortcuts to save yourself money, and you are providing your shop a competitive advantage at the expense of the customers' safety. That is where every attorney and judge will go.
Beside the risk of system failure, which I personally believe to be SUPER rare, under torquing and over torquing can lead to corrosion, and or reducing the lifespan of the components.
Regarding lug nuts, improper torquing can lead to premature rotor warppage and failure of other components.
Here's what you need to know about torque:
1) Formula 1 teams torque everything. Its the right thing to do. It's what good mechanics do.
2) Threads, mating parts, and the interface between the underside of the head and the bolt or screw head must all be CLEAN and lubed with something. DRY torque means factory lubrication (like when the parts were brand new). WET means coated with paint, sealant, grease etc. There are no torque values for chalky, corroded, rusted bolts. The friction associated with the threads and the area under the head could react more than HALF of the total torque you apply. Forget about good torque wrenches or good torque wrench technique. If your hardware isn't clean and slightly oily, your torque values could be WAY off (i.e. zero preload- see next point)
3) Engineers don't care about torque. We care only about bolt preload. And we really do need what we say we need. We preload bolts to prevent parts from seperating. Technically, if you applied no torque (bolt head just touching or hand tight) ANY load would seperate the parts. In a head, when you have 20,000lbs (force) from cylinder pressure trying to lift the head off the block, the mechanic must produce 20,000lbs of clamping force by preloading the fasteners to keep the head on the block.
Some parts can fail mechanically when seperated. They are bolted together because they are stronger together. Some parts require contact pressure for sealing (water pumps). Sometimes we need contact pressure to keep moisture, which causes corrosion, out.
4) Think of bolts as a row of buttons on a tufted sofa back. Pull the buttons too hard, and the material festoons between the buttons. That can happen with metal. Too much preload can produce gaps. So more isn't better,
5) Now think about your lug nuts/bolts. When you are driving and turn the steering wheel, the lugs keep the outside wheels on the car. Each lug in turn will see a greater percentage of that total load. The tighter bolts loads will be higher. Under torqued bolts could go from no load to load, no load to load. This is tremendously worse for the fatigue life of the bolt. Its better to have fatigue cycles above zero, than tension and compression (positive and negative load). All the components that fastener is attached to feels this same sensation.
Conclusion:
Improper torquing is a big deal about to get bigger. Manufacturers are designing lighter weight engine componnents to save weight. They are using more non-ferrous materials in cars. Composites, especially carbon, are very sensitive to torque, corrosion, and require careful sealing.
If you are a pro, suggest your shop hosts a "Torque Stand Down". Spend one hour of shop time to reinforce the importance of working clean, using your torque wrenches, and knowing where to find the correct torque specs. You could easily put a poster on the wall with the basics - dry torque vs socket size. Pretty sure I have already posted such info. Entitle your poster "We take longer to fix your car because we care about your family's safety".
No mechanic has hands sensitive enough to produce reliably torqued fasteners. Any mechanic who resists, challenge him to torque a bolt to 65 NM. Give him a generous +/-10Nm (way too much). Check the torque by tightening with a Snap On digital. If it moves at 55 he failed. Now loosen it. If it doesn't move at 75 he failed. (this is slightly unscientific but it will make the point).
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