Yep, it does take time to go to the store (and heck, which store?). Heck, it might even cost energy (ie. kJ) too. However one can perhaps also order online and then it only costs the time to order the product plus the waiting time. Which is idle time, not active time. There's a nuance difference between that. Consider a gazpacho. It requires the soup to be served cold, so after it is basically prepared you need to put it in the freezer. Or consider you marinade something such as tempeh which you stir fry afterwards (the latter of which is active time, the former idle time). Whereas if you're an hour in the kitchen actively busy preparing things, that's active time.
