A well-built large city isn't just going to be 100% biking and walking paths, it's going to have streetcars, light rail transit, subways, and buses as well as roads with cars. The difference is that people shouldn't be forced to commute across the entire city to get to work because you decided to cram all of the commercial zoning into one downtown core.
Isn't the point that they should be, if that's how I choose to build a city, and they don't have to be, if you choose to build it otherwise? The entire point of a sandbox city-builder is, I assume, that it's a sandbox, and not a dogmatic interpretation of a childish Reddit meme.
If you think Simcity and Cities: Skylines are realistic depictions, then ask yourself why Simcity famously has no visible parking whatsoever (or don't: the devs are on record saying they excluded it because it made the cities look terrible, there's no need to speculate here), or ask yourself why Cities: Skyline added car pokeballs (where drivers get out of the car and put the car in their pocket) or straight-up delete cars when traffic gets too heavy.
It's the opposite, no? Most city builders cheat to be able to be fun. Like, with the amount of roads one build in Sim City, half the map would have had to been parking lots to account for that amount of traffic. But that's boring gameplay, so they remove that constraint to make a fun game. Aka you never have to deal with the consequences of making your city car dependent.
Edit: See another comment from CalRobert about exactly this.
Cities Skylines with all the DLC and the right transportation mods gets pretty “realistic” in that you can build a transit paradise but the car still exists.