Of course they weren't. Mine was always talking pre children about how he'd helped out with his nephew when he was a baby, driving him round when he wouldn't sleep at night. With our children he did this precisely 0 times.
I thought we had a modern marriage, we were friends, equals, he cooked and did washing etc. Once we had children, it all went up in smoke. Not saying there weren't any red flags, but they were more obvious in retrospect than before the fact.
This was my experience too and I suspect it is quite common.
My DH and I lived together for years before we had children and we split everything evenly - cooking, housework, shopping, life admin, etc. There weren’t any giant red flags - he certainly didn’t expect me to pick up after him or iron his shirts, for example.
But then we had a child and the amount of free time available reduced significantly while the amount of housework and life admin doubled. It turned out that my DH was very good at looking after himself and his environment but wasn’t interested in the drudgery involved in looking after someone else.
This won’t work in every relationship and I certainly wouldn’t advise anyone with a lazy husband to give up work, but the one thing that got through to my husband was threatening to quit my job. I said I wasn’t prepared to do 90% of the housework, childcare and life admin while working full time and earning 50% of the money - if he wanted me to be a 1950s wife/mother, then he needed to be a 1950s husband/father. That scared the hell out of him because he certainly didn’t want the pressure of being sole breadwinner and definitely didn’t want to lose my salary. Things did improve a lot after that.