Hi Old Schooler (we of similar schooling, no doubt). Ahhh. If only...
I am a strong believer in pragmatism, the study of what actually occurs despite what we engineer or design to be.
In Colorado, CDOT still attempts social engineering (e.g. our new 'Traction Law', which is neither understood nor enforced). When that fails, because folks cannot afford winter tires or believe their cars superb without them, they salt the daylights out of the roads. Magnesium chloride becoming too expensive in this tax-averse state, they've now begin to use brine solution, which is even more corrosive. They combine those salts with gravel, not sand. These salts rots exterior chrome, the gravel pounds paint senseless, and anyone wanting their shiny new car to stay that way better keep it garaged. I buy a new windshield annually, new headlights every 4 years, and have long since stopped weeping about my paintless front end. The price of driving to ski on snow days, which I sacrifice my car to do.
Every year, our major highways get repaved. I suspect the polishing effect you describe involves concrete roadways, of which we have few. Most are asphalt. They crack, they heave, they split, they are poorly paved to begin with, the lane markings disappear quickly, and each year the road miles ignored by repaving increase. The luxury of studs polishing our pavement would be a fantasy here. First, a small number of drivers own any winter tires. Second, few of them use studs. Third, the asphalt is very short-lived. Fourth, we add drivers annually much faster than lane miles. So the 50% theoretical you propose cannot occur. And speaking of costs, as you do, the destruction of our vehicles from salting is a tax far more costly than the road damage, just disguised. When government ruins cars of well-prepared drivers to allow transit of inadequate ones, that is a tax.
Next, look at the socioeconomic profile of our drivers. Many are cash-strapped with soaring housing and medical costs, and cannot afford basic car maintenance, let alone good tires. They still drive. 50% are under or uninsured. Marketing assures them that cars drive themselves. Distractions from phone addiction is epidemic. Few adopt my mantra: drive like your life depends on it.
I'd love it if:
...CDOT only plowed the roads, no sand, no salts, driver be prepared or stay home,
...everyone had winter tires, studded or not. Heck, even if they owned 4WD with good all-season tires,
...a winter driving class was mandatory before getting licensed,
...folks merged right after passing on multi-lane highways, rather than block the passing lane white knuckled and force capable drivers to pass on the right,
...trucks chain up, maintain and manage their braking systems, and keep right,
...rental car agencies rent cars with winter tires (its a horror what they send our flatland visitors out on the roads with!)
But let's get real. Snow driving is a dying art, greed dictates what we are sold to drive, and ridiculously large wheels on new cars make tire maintenance un-affordable. The best we as individuals can do is to maintain our own, and try to educate the rest - the purpose of these forums perhaps. So while we might debate the nuances of whether studs last the life of the tire or provide marginal benefits, its much less important than educating all drivers about their responsibilities to maintain a driveable car.
I personally try to convert at least a few dozen folks each year to buying snows, or hitching a ride with a good and well equipped driver if they want to ski here. You Canadians live with more ice than we do, hopefully the education process is less onerous for you. Here, it's a slowly losing battle. On any given powder day, closure of our major artery to the ski resorts (I-70) is a crapshoot.
When there were far fewer humans here, simple cars, no cell phones, and drivers education in schools, I never thought twice about making it home from skiing. Now, its a casino gamble.
Studs are not the problem. Ignorance is.
You know this, of course, because we're old-school, and in my old school, they taught driving!