Where's the line between technology advancing forward and weeping for buggy whip makers?

Self-checkouts allow several people to check out a few items at once, leaving the cashiers to deal with those with full carts. They are not inherently evil. It's a good technology (when implemented well with functioning machines...)

I'm all for treating employees with fairness and dignity. But expecting employers to not innovate in a competitive marketplace for the sake of keeping employees doing low-skill work makes no sense.

So... where's the line? Do we demand no automation in order to protect these workers? Or do we demand additional safety nets for these workers and the opportunity for them to improve their skills if they so choose?