Well, around Chicago some of the smaller suburbs have a nice little downtown and are on a train line into the city. If you lived near that you might get by just using online shopping and uber if you occasionally needed to go somewhere. There is bus service too but it's not that good.

But in general, and in the larger suburbs yes you would be pretty inconvenienced without a car. But that is true of suburbs everywhere.

You'd be fine in basically all of the inner-ring suburbs except maybe on the south side.