Those are two completely different situations, and it's intellectually lazy to consider them the same just because they're both words that people occasionally m

Those are two completely different situations, and it's intellectually lazy to consider them the same just because they're both words that people occasionally mix up. First, who & whom are more rare in speech than its & it's which are fairly common. Second, there is zero confusion about which one to use with its & it's. One is a contraction for "it is", and the other shows the possessive. These are very simple rules. Who & whom, in my personal experience, don't get as much coverage in the English classroom. I'd be hard-pressed to find people who could tell me exactly when to use those versus its & its, as those come up less in day to day conversation. Since its & it's have very clear rules and are used frequently, addressing the correct usage is important, same with your & you're and their, there, & they're.