Earlier quoted context omitted.
NYC has 30,000 streets and only a handful of days of snow in the year. By having garbage trucks that can deal with a few inches of snow, you avoid the need of buying dozens of dedicated vehicles that will rot 360 days a year.
What you are describing is overspeccing (thus over paying upfront and for maintenance) of the large fleet in order to avoid having a small fleet. Alternatively, the large fleet could be appropriately specced and the small fleet can be “mothballed” the rest of the year, thus preserving its longevity.
The large fleet is “2,230 general collection trucks, 275 specialized collection trucks, 450 street sweepers, 365 snowplows, 298 front end loaders, and 2,360 support vehicles” [1]. Those general collection trucks, together with the plows, constitute a circa 2,300-plow snow fleet [2].
Dedicated fleet means buying 2,000 more snowplows. There is no small fleet option.
[1] https://en.m.wikipedia.org/wiki/New_York_City_Department_of_...
[2] https://nypost.com/2020/12/05/nyc-spent-12m-per-inch-of-snow...