I think my point is being missed though and that is that using Uber as your daily commute is certainly not cheaper than owning a car. I think that's perfectly reasonable to say.
Also I don't mean to imply that Uber is a luxury in the same way Lois Vuitton is a luxury.
In my examples in other comments using Uber as a daily commute option almost certainly costs nearly 1000 or more per month.
Transporting large items, or groceries for an entire family are extremely difficult if not impossible over public transportation. Transporting a group of people (3+) can be approximately the same price on public transportation and Uber without potentially sacrificing comfort, safety, time and effort, many of which can be essential depending on your circumstances.
The cost of using Uber and Public transportation also requires a lot less upfront cost which is necessary for people living paycheck to paycheck and can't afford to spend around $2k on a car, as well as deal with it's maintenance time and cost.
I mean, it's not a luxury good in the sense that you can buy a car, but I suspect many folks have made difficult or expensive to unwind decisions that make car ownership expensive. Classifying transportation where an alternative may well cost more than $1k/mo as a "luxury good" is a real stretch of the word luxury.