Driving is considered to be the default. Most people know what to expect when they drive to work, and conditions don't change all that dramatically through the seasons. And cars are nearly "one size fits all" for people with different levels of physical conditioning.
People wrap their lifestyles around their cars. The last year that I still drove to work, my morning drive was a complex route that involved dropping off my kids at day care and my spouse at her workplace. A lot of people have routines like that. When they were old enough for kindergarten, I walked my bike along with them to school, and continued to my workplace from there.
Possibly a big under-appreciated factor: They know that driving is socially approved. It's like the old saying, "nobody ever got fired for buying IBM." If you drive, and something goes wrong, everybody's sympathetic because it's part of what's considered to be normal. If you ride a bike and a flat tire makes you 10 minutes late for a meeting, now you're the freak who was screwing around on company time.
I believe that unavoidably, cycling to work requires a bit more experimentation and adaptation to make it work for your situation. At the very least, you have to find a bike that fits your body, figure out how to get reliable use out of it, how to deal with weather and seasons, including darkness. If you maintain the option of riding or driving, the choice to ride has to be made about 1/2 hour sooner in the morning, give or take. It's only "simple" if you've been doing it for a few years.
I advocate bike commuting at my workplace. It has gained in popularity, but slowly. I hope some people see a guy like me, relatively slight in stature, not hip or young by any means, as proof that you don't have to be a hero to ride a bike.
I advocate starting with modest goals and figure out what works for you. Start with a few exploratory rides during weekends, to find a good route. Then come to work during the days with the nicest weather. Give yourself a chance to get addicted to it before raising the ante. Chances are, most people will never ride in subzero weather, so I don't push that at all, but I do carefully explain why it's not as insane as it seems.
I recommend e-bikes. The people who can pedal a conventional bike without unbearable effort already know who they are.