It can be about predictability as well. If Amazon says two days, it is usually two days. I arrange the purchase for a day when I don't work or work a short shift. If it is a valuable product that requires someone to receive the parcel, I don't have to deal with shippers who force people to use a pickup point that is a 15 minute drive away. (I don't drive, so that is usually problematic.) At the end of the day, in my case, it is more about receiving the product than getting it right away.