Like on a motorbike I tend to tweak slow speeds with the clutch only and leave the throttle in one position most of the time.

With an automatic car since the brakes are not binary and automatic gearboxes have often forward creeping I only tweak the brakes. Helps to force the gearbox into 2nd gear as well for even slower creeping.

In fact, I think automatic gearboxes reduces traffic jams as fewer parts to think of so less likely to accidentally make a mistake and cause congestion.

Wonder how many jams are due to accidental stalling a manual gearbox.

Traffic jams without an automatic gearbox is no fun. (or even less fun)

If, left in drive gear, yes. However, many cars have several options.

In my current car, a Honda, rhe lowest gear will just creep along, next gear up will slow the car rapidly on gas pedal release.

Both gears are very well chosen for traffic. I rarely apply brake.

Not with the regenerative braking in my hybrid.