It very very heavily depends on the part of the modern world that you live in. A lot of ostensibly well-off, relatively dense areas in North America are completely unlivable without a car. Public transit isn't reliable enough, distances between your house and various amenities (parks, shops, transit) are too far, and roads are too narrow for walking (no sidewalk or shoulder and travel speeds of 60+ km/h in many places).
Yes, it's possible to go without, but it's so difficult, or requires such a different lifestyle that it's just not practical. The choices have already been made, and there is no going back. I was raised by a single mom, and there is no way she could have provided for us as well as she did without a car. And she went through some real difficulties to have a working car.
[edit: I should have added that this is in the US. It may be different in different places]
Generally though, one thing of public transport that gets overlooked is that a) you schedule becomes tied to public transport, and b) you have to deal with people. Because of noise and labor regulations, public transport for short trips does not run at night. Also you can get delays due to passengers causing holdups, and so on. I honestly personally much prefer driving over public transport.
This is a big problem with a lot of systems, especially the north American ones, but it isn't an inherent flaw in public transit. The more it is used and the more it makes itself available and frequent the better it works overall.
I need a car, but I don't buy them new. I buy used cars that may have some cosmetic flaws but are fundamentally sound. I pay cash so I don't have a car payment or interest expense. Insurance is lower, and if it gets dinged or scratched in a parking lot I don't care.
1 A job where WFH is not an option (either because it's physically impossible (e.g. service industry), or because even if it is physically possible they are at the whims of their boss)
2 A long commute
3 Poor mass transit; even if there is "okay" mass transit both where they live and where they work (already unlikely) there is unlikely to be mass transit connecting the two.
4 Multiple jobs, at least one of which doesn't fit any available mass transit designed around 9-5 commuters.
I own a car that cost me 700 pounds. My annual insurance and tax are 500 pounds. The car basically requires 0 maintenance. It will break in approx. 5 years and I'll buy another one.
I can go to the countryside, visit friends and family that do not live near train stations, go to large supermarkets and buy in bulk, and generally just go everywhere more quickly.
I like this. It's nice. I'd pay 500k over a lifetime for it. It allows me to do many things I couldn't otherwise. Thankfully it only costs me something like 50-100k.