Exactly. Not to mention only around 30% of women owned cars and drove in 1975 compared to around 70-75% now. Using public transport instead of a car for groceries, errands, commutes to-and-from school, appointments, medical visits, social events etc. were much much more time consuming and took a huge proportion of the day for a mother than they do now.
As @user1471429429 says, appliances and conveniences since then are saving us more and more time each cycle - better hairdryers, washing machines, dishwashers, robovacs, heated dryers, vacuums, cleaning products, slow cookers, air fryers, blenders, mixers, baking tools - all of those things have cut down the time it took mothers to use them since 1975.
Nowadays can do anything from order groceries, takeaways, stream a Disney film, open a credit card, bank account, book an appointment, get something fixed, order everything from birthday and Christmas gifts to an pair of emergency sports shorts to arrive the next day on your doorstep in a matter of seconds with a click of a button. Back then you had to handwrite postal letters back-and-forth, attend faraway shops for niche things, wade through paper correspondence and applications from schools or sit through long in-person appointments for virtually anything. You can literally select and buy all your Christmas presents and your family Christmas dinner to arrive the next day all within the space of about an hour.
And as the poster said, generous maternity leave, increased holiday allowance and flexible working patterns which were minimal or non-existent decades ago for women have all helped to make more time for women now. Women who worked back then were far more time-poor doing identical tasks to the same woman today.
Women have always worked throughout history. Maybe some affluent households could afford to have a stay at home Mum and the % of these women as part of the population was higher but there has never been a time throughout history where a sizeable proportion of the female population did not work. And a lot of women who didn’t have formal employment, often did cooking, cleaning, ironing, caretaking for neighbours, friends or the community to gain some more household income. I attended primary school in the 80s and bar one, don’t recall a single one of my friends (upper working class/lower middle class) who’s mothers didn’t work.