Just for the record:
Hazard Light Use - AAA Digest of Motor Laws
And also, REAL winter tires are very different than M&S or Summer designated tires because of tread compound ("the rubber stuff"). There is more natural rubber in it and the hydrophilic property differences are huge. Yes, the tread design is also a factor.
And just for the record, tests (as in actual tests on road surfaces of all different types) on ice, snow and water don't show substantial differences for skidsteer tires that are grooved or siped after the fact,for very good reasons based on sound physics and chemistry: Its the rubber stuff again. In deep wet packable snow, there can be a small traction improvement, but the effective surface friction coefficient is nowhere near what a real snow tire can do.
The downside of REAL snow tires is worse fuel economy (rolling resistance) and tire longevity (treadlife). Sorry to have to inform all them there backyard injineers, but real tire engineers at all the tire development centers know this. And I've been one of them. A traction test trailer is all you need and a hockey rink to end the rumors, legends, and tales. (Along with lots of tires to test).
And, btw: 4wheel drive is just that. Everybody has 4wheel stop, but because of required brake proportioning (F to R), you don't really ever get to use max rear brake. And ABS beats 'pumping the brake pedal' EVERY time, but you have to engage ABS by pressing the pedal HARD. Nobody can 'pump it up' 10 --> 15 times per second. NOBODY.