"winter tyres are uneconomic."
I question that assumption.
You could buy softer compound "All Season" tyres. All seasons are not as soft as full winter tyres so will last a decent amount of time, especially if you just put them on between Dec->Feb. Note that softer compound tyres grip better regardless so you get a safety benefit by doing this
If you have a front wheel drive car, it could be argued that 90% of the benefit comes from just fitting two at the front. That's not to say it wont encourage back-end slides, but you will get more forward and braking grip overall.
Winter tyres are only strictly law in a few countries, not including Switzerland and Germany. In those countries, the laws are phrased to say "suitable tyres for the conditions". So if it's snowy, you should not be driving on summer tyres. And if you have an accident you are in big trouble with the cops and your insurer.
On the continent, they just take the sensible approach of putting on suitable tyres over the winter. I'm thinking seriously about this myself, though I have actually just bought some auto-socks!