Taxes have many purposes, and one of them is incentivizing preferred behaviors. Why should we discourage working from home? Is wasting a significant part of your life commuting to work really that good for the society? It's certainly not for the environment.

Also, there are many hidden drawbacks of working from home – it's more socially isolating, the work-life balance suffers, setting up a home office may be costly. I can imagine such a tax making working from home not worth it for lots of people.