Granted, I have never lived in NYC or a few other major U.S. cities with adequate public transportation.
But I lived in Chicago for 10 years as an adult, so I think I can safely render my thoughts on the subject.
At least in Chicago, it is only convenient to take the "El" if you live near it. And even then, it is a pain in the ass. Takes longer and is annoying as hell. When I was having car issues, was happy to take it. But I could just choose to drive in an hour earlier, beating some of the traffic to the Loop. And pulled into a garage, which at the time cost $150 a month, or $12/day. I know prices have gone way up now, which thankfully I avoided by getting a job in the suburbs. But unless you live very close to the El, it is a pain, especially during winter.
My former brother-in-law is a lawyer, worked in the loop & probably made at least $300k a year. He & his family lived a block from an El stop, and he would take it to & from work several days a week, just for the convenience factor. And he only lived a mile from myself & the former Mrs. Wiggum. For me, I would have to take a bus six blocks, taking 10 min. Then, damn near an hour on the Brown Line train just to get to the loop. Google it if you wish, the schedules are online. Pain in the freaking ass.