I think anyone alive today DID have the choice. My own mother would be in her 90s if she was still alive. She was never a SAHM. My brother was born late 50s and I was born early 60s.
Before having children, she had a full time job/career in the Town Hall. She couldn't return to that job after children because it was full time post (thank goodness times change) - she always regretted not being able to return to the job she loved! She had children late in life (I think she was 40 when she had me), so she was well and truly a "career" woman!
So instead, she retrained as a teacher. In those days, it was possible to do that via the self/home study route, which is what she did during pregnancies and whilst me and brother were toddlers. She qualified as a teacher and then started work, part time at first and then full time once I went to school, with my grandparents doing the "wrap around" care for half an hour before/after school, as Mother worked at a school nearby so short travel time/distance. That was as far back as the 60s. She hated being a SAHM, hence why she changed careers.
There were options and alternatives. I'd say it was 50:50 between school friends' mothers who worked and those who didn't, that was late 60s, early 70s. My best friend's Mum certainly worked, but I can't remember where or whether it was full time or part time, I just remember that whenever I went to their house, she was seldom there!
This thread has just prompted me to ask my OH about his mother, and yes, she too wasn't a SAHM, she didn't have a career as such, but always worked, mostly it sounds, as a book-keeper/administrator, but she couldn't "settle" because her husband was in the forces, so they moved house every 2/3 years depending on his posting, so she basically found whatever work was available wherever they were.
But if you go back further, lots of wives DID work in some form. A lot of women used to work in the mills/factories during the industrial revolution, or worked on farms, or "worked from home", such as seamstresses, "home" based businesses like dairies, shops, bakers, etc.
I think it was a relatively short period in history where it was the "norm" for wives to stay home and "just" look after the house and husband.