I'd also like to add to this bug that it's not just employees either that's shoveling snow, but my own Sims as well when left with autonomy will sometimes leave their tables just to shovel snow.
In addition to the waiters constantly going outside to shovel snow, the customers also go outside while waiting for their food. And my own sim (restaurant owner) keeps going outside to play in the snow or shovel the second I don't have something queued up for her to do. Really annoying that I have to keep changing her out of her cold weather outfit.
