[KaVir]

One of the things I liked about the is that they really tried to address what sort of impact a high prevalence of magic would have on society. In Eberron, high-level magic is very rare, while low-level magic is very common - primarily due to the (magical guilds, each with a monopoly on different areas of commerce) and the magewright NPC class (the idea being that most people in the world belong to the common NPC classes, with players being among the few who are exceptional enough to belong to PC classes).

Thus House Orien operates a postal service, and they will indeed use teleportation if the price is right - but teleportation is a higher level spell, and can't be used to transport large amounts, so most people would rely on other means such as the lightning rail (an elemental-powered train) or a House Lyrandar airship or elemental galleon. However if it's just a message you want to send, you could visit a local House Sivis enclave and use one of their speaking stones to instantly transmit a message.

It's the same with other things, such as the magical lanterns used throughout the continent, 'featherfall' tokens for those living in Sharn (City of Towers), etc. I think the author must have sat down with a list of all the low level spells and thought to himself "What would society be like if most people had access to these spells?"