@ThoseTolerableNoobs:
Only the everyday person does have magic. How else could a common prisoner be able to shoot fire from his hands- granted not much more than it takes to light a campfire or injure a large rat- and heal small wounds at will?
As for transportation, that really depends. It cost about as much in Morrowind, an Imperial backwater, for a person to be magically teleported halfway across the island of Vvardenfell as it cost to ride a giant bug whose shell had been hollowed out the same distance. So magic may not be a particular "rich man's game" in that regard.
So health. The thing that can cure diseases instantaneously and cheaply, as well as heal minor or major injuries depending on the mage's ability, either through spells or potions (which are a type of magic, broadly kinda sorta). And I don't see why, when you have a force that can move and change the fabric of reality, a need to terraform a large area to make more habitable land would require people to come up with new mundane devices when you have two large magical organizations in the Empire alone.
And let's look at guns vs. mages for a moment. Oh, sure, maybe a person could fire a musket from an unspecified distance and drop one mage, either through injury or successfully killing him outright. However, he is now known to be present, up come the magical wards that prevent physical objects from hitting you, unless you're talking one musketeer against one mage, and assuming a mage on a battlefield or heading to one wouldn't have pre-set his wards. So if a single musketeer ambushed and killed one mage, then sure, I'l give you this. But in the case of one gunner vs. many mages as soon as he is starting to reload the whole area will be lit up, or in the case of many gunners vs. many mages if any or several survive the initial firing then continue as before and suddenly there are no gunners but piles of char.
Trade and commerce: I can hand it to you that perhaps people would make mundane means of mass production. Sure, why not?
However, while Tamriel can and should culturally and artistically advance, I'm still saying that not only are there some weak points in your showing of the need portion above, especially in you "magic isn't available to the common man" statement that is really just not even a thing at all, but you haven't addressed the resource thing at all. need meets resources, magic is an unlimited resource in the world at large, if not during individual sessions of use. That, more than a lot of the rest, is the killer of your assessment. Why would people seek out a resource of (to us) unknown rarity, that may or may not be hard or easy to obtain and may eventually run out and probably only have a few individual functions, when they have the literally boundless and unlimited magic to draw from? I only have one counter myself, and that's an individual's skill at casting spells. Someone who is just not good at a spell to light fire would use flint and steel, where someone who was good at it wouldn't.
As a fun, semi-related note, I'm going to expand that even in it's weapons and magic Tamriel should advance, but again, needs/resources. Check this http://www.youtube.com/watch?v=7CfyU1mOZ1Ehere for kind of what I mean.