yup... worst case for the wizard is to be exactly equal to the fighter... that is the issue
In this scenario. Same idea if it was a druid and wizard who prepared nothing for monstrosities. But that doesn't mean wizards are better than druids.
If it was something that required a strength check, like pulling a stuck lever or pushing aside a boulder, then the fighter would have a clear and distinct advantage.
wizards prep spells after every long rest
But only the ones in their spellbook, which only adds spells through DM fiat or leveling up. If the wizard never chooses it as a level-up option, they won't be preparing it mid-adventure.
wait... why would they 'waste rounds' they don't have ANY damage or combat spells or cantrips? that seems a weird scenario.
Is it weird that a wizard would try to use their action for something other than damage? In fact, it's often argued the wizard's combat niche is specifically non-damage effects.
how is the wizard worse off for being suprised?
They have lower AC and HP. And since they're surprised, they can't use a reaction or first-round buff to mitigate incoming attacks. Fighters needn't activate any of their defensive abilities. That's the power of resourceless passives.
what we can do is look at the options we have to make the characters.... the fighter can do damage take damage and use skills... the wizard can do damage (admittedly less then an optimized fighter but not a lot less) take damage, use skills AND have access to an entire sub system that changes the game that the fighter does not.
But that's not all a fighter can do, that's just what the class itself provides a character. But a fighter character can also create clockwork devices, communicate with small and smaller beasts, attempt hiding in light rain, fog, etc. Not to mention they do have a small catalog of spells they can acquire without a spellcasting subclass.
And while these are afford to other characters as well, that still gives the fighter character options. Potentially better-used than if the wizard had them. Considering martials use ability checks more often than wizards, a halfling's lucky has more opportunities to be useful for a fighter.
What I'm trying to say is that choosing to be a fighter doesn't mean you choose to disengage completely with exploration or social. And you're given options you can choose to have. Some of those options work better for fighters, too, so it's not a one-to-one benefit for wizards.