I think there's a demand for a device to equalize the sizes of electrical cord prongs.
Imagine a gizmo similar to a bit sharpener into which you insert the plug needing adjustment. A cutting wheel inside trims the larger, neutral, prong to the same size as the other one. It would probably have two cutting wheels to do both the top and the bottom.
I'd be willing to pay, oh, say, $14.95 for such a machine. It would save an immense amount of time compared to massaging each plug with a Dremel tool.
Heck, hardware stores could offer it as a service when you bought the offending, crippled, tools - similar to free gift wrapping!
And as for safety, it's not an issue. If grinding down the neutral prong WERE problematic, we'd certainly see some cautions in the 8-page safety instruction booklet that comes with and electric clock along with all the other admonitions such as "Not for use in the shower, Do not puncture, etc."