Mamie - yes my daughter and OH do the same. Take it in turn to leave early and get back late. And it works very well - although it takes a lot of organising, compromising, and more. Why should the mother always be the one to drop their career (well most of the time. Easy enough to be the other way round if the father does not have a career, or is happy to drop it). Not easy either to go back to the same level after maternity leave. My daughter dropped a couple of places, but very soon 'caught up' and became a partner of her firm. Had she stayed at home for 5 years or more, she would have had NO chance at all to get back in ever, possibly, as the world she works in moves so fast.
Kittylester- yes I can see what you mean. But few people have the training, experience and the ability to do what she does. It is not as if, if she had dropped out, somebody could have just walked into her shoes.
For instance it takes a huge amount to train a Doctor. So many of the women then become GPs, and then give up or work a few hours a week or part-time- a huge waste of resources and training, and a huge loss for the NHS and us..
Same for nurses, dentists, teachers, etc, etc.
My daughter giving up her job would not have given an un-employed person a job, I am pretty sure. And she does employ a full-time properly trained NNEB nanny (at huge cost), and a cleaner + washing/ironing service, so her working does provide employment for others.