You seem like you're working with some skewed facts. No one is claiming that Meteor Swarm is the top end of a wizard's single target damage. It's an AoE spell. Comparing the fighter's single target damage to an AoE is like claiming that missile strikes have a lower chance of killing a specific target than sniper bullets, so therefore missiles are clearly less dangerous than bullets from a sniper rifle.
It's not that Meteor Swarm itself is supposed to be all-powerful mechanically, but it's often used from a narrative argument to say "See, the wizard can just summon meteors while the fighter plays with sticks."
But the point is that the "meteor" is different than a realistic meteor in that a CR 2 human can decently hope to survive a magical meteor point-blank. So clearly magic can't be considered a one-to-one with their realistic counterpart.
The wizard has a myriad of options for dealing with the bandit captain. Just for starters, cast forcecage on him and then kill him (or not) at your leisure. Unlike with the fighter, if the bandit survives the opening salvo, they can't so much as hit back.
While it should be no surprise a level 7 spell can incapacitate a CR 2 creature in a single turn, it also shows another point against the wizard's "almighty" power.
During a fight, it's great to be able to incapacitate a creature with one action and keep them from doing melee damage, potentially kiting them, etc. But this "powerful" cage is actually...very bad at being a cage.
Setting aside the size restrictions, it only lasts an hour. This means forcecage is capable of being useful in keeping someone in-place for about 4 hours at max, taking up 7th, 8th, and 9th-level slots. You could knock the creature unconscious, but it will wake up within 1d4 hours, meaning the wizard still has to monitor them lest they break free.
All this, and thinking about the types of threats where you would like to use Forcecage, would it really be worth it? A balor has the Charisma and magic resistance to leave the cage anyways. A pit fiend variant can summon devils and still has access to its fireball/wall of fire/hold person. A lich can guarantee their plane shift with a legendary resistance.
High level threats aren't as susceptible to this kind of restraints and low-level threats would happily eat up your 7th-level slot.