I don't see why the Druid would be armorless, and since they can usually hang back and cast at this level anyway it doesn't matter as much either. Nor is it reasonable to talk about shields here and two-handed weapons later. No Schrodinger's Fighter, please.
1) Druids start with 2d4 x 10 gold, average 50 max 80. Studded barding is 50, a spell component pouch is 5, and hide armor is 15. Thats about a 19% chance to buy these three items and nothing else, leaving you with a club, sling, and rocks for fighting with.
2) Druids have 2 first level spells at first level. Hanging back and casting at this point is basically contributing nothing to the fight.
3) I didn't realize the Light Flail was a two-handed weapon. Oh, wait...
Huh? Since when are greatswords one of the worst weapons in the game? They're tied with falchions for best MWP damage potential at any level, and at level 1 are guaranteed to have the highest. Your hyperbole here unreasonably inflates the Fighter's potential; greatswords are very nearly as good as it ever gets.
Neither the 4 HP kobold nor the 5 HP goblin cares about whether your average damage per hit is 7.5 with a light flail (8.5 two-handed), 9 with a guisarme, or 11 with a greatsword. Likewise, later on they won't care about the extra 2-4 points of damage you get from using a Greatsword over something else, depending on how your charge multipliers work out. It is notable, however, that the Greatsword lacks both reach and the ability to trip, two things that are far more valuable than 2 points of damage at any level.
And an extra +1 on Will saves.
Assuming 10 Wisdom and no feats boosting Will saves, or even abilities just giving outright immunity to certain effects like Elves being immune to Sleep and having a +2 against everything else in the Enchantment school.
OK, cool, arguments from experience won't go anywhere here, because it'd just be two players comparing their respective tiny pools of anecdotes.
The rules actually state that you start with the base creature's block and then lists an exhaustive set of changes you can make to said block. A wolf AC starting with anything other than 13 Strength, 15 Dexterity, 15 Constitution, 2 Intelligence, 12 Wisdom, and 6 Charisma is a houserule.
To the extent that any mundane class has a chance to shine, that chance is in early levels. I am not convinced that Fighters specifically ever get that chance.
Well, that's your problem.