But not everyone can use magic I guess, probably there are different classes like most fantasy worlds (with their own skills). And even then, if its cheap mages can save mana by using matches instead of casting magic; it should be better than buying mp potions. There are lots of simple things we use nowadays that would be revolutionary on a medieval fantasy setting like that, even pastic bags that weight basically nothing and if well tied will not get the goods inside wet would be an amazing find.
And then again, if they use the good old fantasy trash processing methods (AKA slimes on a hole) it should not pose any issue for the enviroment.