Wizards have greater flexibility in terms of resource management than most classes, because they can opt to rely on the resources of other classes.
Let's say that the party comes across two giants. The frontline engages the giants.
The wizard can choose to cast cantrips and let the frontline deal with them, which is likely to cost the frontline more in terms of hit points and potentially other resources.
The wizard can expend a trivial resource, like Tasha's Hideous Laughter, to likely disable one of the giants and make it easier on the frontline (which will likely save the frontline significant resources).
The wizard can expend a significant resource, like a 6th level Hold Monster spell, in order to probably trivialize the encounter, likely resulting in minimal resource loss on the part of the frontline.
The fighter can ask the wizard to cast a bigger spell, but they can't really do much about it due to their role and capabilities. The wizard can choose not to cast a bigger spell. If the fighter refuses to tank for the wizard, assuming the monster doesn't focus on the fighter anyway, the wizard can Dimension Door away and leave the fighter to fend for himself. The fighter can't really get away from the giants, since their movement speed is most likely greater than the fighter's.
Now, I'll grant you, this party dynamic sounds more than a little unhealthy. I might not want to play with these guys.
However, this isn't about player dynamics per se.
My point is to illustrate that the power imbalance between wizards and fighters extends to a very meta power imbalance between the player of the wizard, and the player of the fighter. At a healthy table, this may never be an issue, since the wizard player shouldn't ever opt to abuse that power imbalance. That doesn't mean it doesn't exist however, and I don't think it should be there to begin with. A more robust fighter design would narrow or even completely eliminate the imbalance.