I have to shower every day, why would I choose to do it before a hilly bike ride rather than after?Riding a bike does not stop people from picking up illnesses like a cold or the occasional virus, by far the most common reason for absence. And everyone having to shower on arrival would knock a massive hole in the environmental stuff.
And why on earth would people need to shower after a five or six mile commute? It isn't a Grand Tour mountain stage.
Also, in the UK for 2/3 of the year there's no way I'm wearing anything that's suitable for work on a bike - it'll be soaked.