You miss the core class features. Which are however many spells you know (lots for divine classes, two spells per level for most casters). And I would absolutely call most spells as complex as any of those champion features.
The fighter gets a 17 core class features plus 7 feats/ASIs, in terms of number that is more than most if not all casters:
Fighter:
fighting style, second wind, action surge (1), ASI, martial versatility, extra attack(1), ASI, martial versatility, indomitable (1), ASI, martial versatility, extra attack 2, ASI, martial versatility, indomitable (2), ASI, martial versatility, ASI, Martial Versatility, action surge(2), indomitable (3), ASI, martial versatility, extra attack (3).
A Wizard gets 5 core class features and 5 ASIs:
Spell casting, arcane recovery, cantrip formulas, ASI, ASI, ASI, ASI, spell mastery, ASI, signature spells.
Now of those, spell casting is the most complicated and a lot of the fighter abilities are improvements/repeats of earlier abilities but a fighter has a lot going on especially if you use feats to expand the beyond the class and subclass boundaries.