[TeMPOraL]

I haven't been to shop with baggers, so that time is more-less constant for me (except for the pressure to bag faster, which isn't present with self-checkout). However, the cashiers are absurdly fast at scanning. Their workstation is optimized for this, and they scan through things faster than I can move them into bags. Even without any exceptional circumstances that make you wait for assistance at self-service checkout, scanning speed alone cuts the time per customer at least by half.

[zamnos]

On a per-item basis, absolutely, but what's the number of self-service checkouts at which they faster simply by having a much larger number of kiosks? Having 10 check stands open for 10 customers, each with their own employee is inefficient, but having 15 self service kiosks open isn't out of the question.