I think the tech level is overall low with the high level tech being the result of a unicorn's individual magic with little mass manufacturing. Flim and Flam have a magic powered automobile/apple harvester but if you were to give one to an average pony it would be useless as they don't have the magic and knowledge to run it so mass production of automobiles would be pointless. Trains going to Canterlot are powered by coal, or magic but the train going to Appleoosa was not, which is sensible if you think how a tiny frontier town has fewer resources then the capital, so the rail line would be out of date There just seems to be a large disparity although in Ponyville at least there is also quick advancement, which could be a result of Twilight being there seeing as she is both powerful and well connected.