I agree with chesedname. There is good reason ownership splits will often be 51-49 (or even 50.1-49.9). So there is one final arbiter where disagreements arise, despite a near equal ownership stake. And I agree that 50-50 ownership stakes disproportionately result in disputes, whether they land up in court or not.
But all these explanations are really secondary. Like several other posters have pointed out (and quoted meforshim and gedolim) throughout this thread, it is the Torah that defines the roles in marriage. Halacha defines who is in charge. I won’t repeat what others have already pointed out earlier in this thread regarding specifics of who’s in charge.