I wonder what explanation "experts" give for power cord differences - that will be fun.
I'm no expert on building or designing power supplies and nor do I work for a utility but one can't help thinking it might be a combination of;
1) Dirty Power (perhaps caused by other home appliances)
2) Inadequate power supply design
3) Ground loops
Since manufacturers are always looking to reduce cost to meet a competitive price point I suspect inadequate power supplies are quite often the culprit. After all a consumer is more likely to buy an item if it has an expensive face plate than if it looks cheap but has an expensive power supply.
Of course it requires that you believe that good equipment design should trump the need for non standard power cords. I have a power conditioner and it helps on one of my components - I still blame the component design however, and do not ascribe exceptional properties to the power conditioner or its power lead.
So we agree in one sense but disagree as to the cause. In the same way I would blame equipment design and compatibility in the case that the interconnects or speaker cables made huge improvements (again I blame the equipment or my poor choice of what to cobble together rather than ascribe amazing audio properties to mere wires)
Just a different viewpoint - no flame intended.