It's also realistic though...
How could the marketing manager of a key global campaign easily job share, you'd have a split vision and for the launch you need proper, detailed direction that cannot always easily just get handed to someone else?
What about a sales director who has to travel to cover her territory?
Or a medical doctor who needs more intimate knowledge of her patient than the more family-friendly "transaction" roles like a salaried GP or radiographer etc?
Or a mental health psychiatrist where her job is to assess before sentencing?
"Sorry dear, your your hip replacement surgery will be handed over to my job share at the 5th hr because I have the school run to do"... Or, "sorry judge, I haven't had time to do the psychiatrist evaluation about reoffending risk because I only work Mon & Wednesdays so you'll have to wait twice as long for me to do it"... Or, "what do you mean I need to be at the local planning permission meeting as the architect, I don't work Thursdays"... Hmm.
There are often genuine business reasons why job roles in many sectors aren't easily split. It's no coincidence that they tend to be the male dominated ones.
If my child had a job share teacher, mental health or medical professionals.. it might work if the people and job enabled them to work as a team. Sometimes it just doesn't work.
This disadvantages women, sure, but also anyone who has any sort of caring commitments or something outside of work which isn't protected or recognised by employers (caring for an elderly neighbor; owning a horse; checking in on a neighbor a few times a week).
Low skilled, transaction roles are entirely different than others.