I live on a street that is a designated bike route and "main drag" for commuters, and right now my "office" looks out onto the street, so I see a lot of bikes. According to what I've seen, people commute on practically any bike that has wheels and is capable of forward motion. Prior to the covid, I was a daily bike commuter myself.
Over the years, I've helped a lot of people with maintenance, and have volunteered for a charity that fixes up bikes for poor kids. So I've seen my share of what they used to call "department store bikes." My view of the cheapest bikes is that they actually come in a couple of levels: 1) Those that can be repaired and kept operable. 2) Those that can't. The ones that can be maintained are often hard to keep in tip top shape because things don't fit very precisely, and it takes some futzing to get a satisfactory adjustment. For instance the cheapest cone bearings are this way. The Park Tool website suggests to not even try to get them perfect. In turn, this might be OK for someone who is confident in their mechanical skills, but frustrating for a beginner who is reading one thing in online tutorials, and experiencing quite another on their bike.
And don't get me started about cheap brakes.
The bikes that I ride are thrown together from old parts, but they were of good enough quality to begin with, that they are virtually maintenance free except for consumables like tires and brake pads. And adjustment is a breeze.
Americans have some weird attitudes about the relationship between business and pleasure. For this reason, you see things like bikes (and cars) that are more fancy than they need to be for the purely utilitarian side of their riding. What's not obvious is that while riding to work, they are also having fun. For this reason, they are not adhering to the lowest common denominator of what they strictly "need."
It's a personal choice. The balance between quality, security, and cost, comes down to every cyclist and the particulars of their commute. No two commutes are the same.