I understand what you're saying, but I don't think that's always the case. It certainly isn't in my experience, or what I've seen from others.:
There is no way that my job (and plenty of others) could be done by 2 people each working a .5 role. For me to do handover I would have to tell the other person what I've done today, which would take almost a day itself, and that second person still wouldn't know those files, clients, cases, etc as intimately as I would (and vice versa). If something happened on a file I'd worked on the day before, they'd have to read up on it to see where it was up to, blah blah blah, before actually *doing* anything. And tasks which I started yesterday they'd have to finish today, and if they want it done a little differently, and it carries over to another day, andthen I'm back, we're back where we started. It's confusing for clients, there's enormous amounts of double handling and duplication, and at the end of the day I can't ask the Court to only schedule my trial on set days for my convenience, or expect clients to be available when it suite *me* as opposed to them, etc etc etc. It simply wouldn't work.
My husband's job could totally be job shared (and was for a while) because once each task is done, it's done! A dedicated 15 minutes spent emailing his co-worker at the end of his day would get the other person totally up to speed on anything that was still under way, or things which needed to get sorted out, or to make sure the admin was up to date, and he could waltz off at the end of his shift confident that his co-worker could pick up where he left off.
But I believe that an awful lot of office roles, management roles, and other senior roles fit more into the first category, rather than the second, where the amount of doubling up in work makes it uncommercial for the business (because a significant proportion of the time they're paying for is spent in handover rather than getting the job done) or ends up being unpaid overtime (either because the employee is trying to finish stuff off so it's not needing to be handed over, or because the handover is getting done after hours, or they're taking calls from colleagues when they're not in, to get answers, troubleshoot or whatever) which is unfair on the staff members and frustrating for their colleagues.
