The fact that it is artificial from the player standpoint isn't the issue, nor whether people in the setting know the spell exists. By the rules, the spell is generally only available to druids. Druids... are not generally folks interested in supporting large urban populations. Being food vending machines is just not their shtick.Mechanically, sure, that may very well be. But the distinction between arcane, divine, and druidic magic is already somewhat artificial.
You say that magic solves problems - that's not really true. Magic is a tool - tools are often used to cause problems. Druids are apt to see large urban populations as a problem caused by such tools, rather than solved by them.