Your argument is as speculative if not more. Resources are not all equal. The ex driver or ex cashier is not going to starve to death. But it's not getting the same salary, if any at all.
The adjustment periods have been on the scale of generations though so you can definitely have localized decreases in well being for large segments of the population due to technological change.
Because people always had something else to do. But what will happen when machines can do pretty much everything? That never happened in history before.
We will invent new things to do. Or, god forbid, maybe just spend some time relaxing and enjoying life instead of working ourselves to death.
...by humans.
> We will invent new things to do. Or, god forbid, maybe just spend some time relaxing and enjoying life instead of working ourselves to death.
With some luck we'll be good pets.