PAL was tuned to the 50HZ of the European net as well as the european broadcasting industry of that time. The way NTCS draws a number of lines within the 60HZ timeframe gives all kinds of interference in combination with a 50HZ net.

If we make stuff that works from DC then we simply select a PSU for whatever region.
But it is also things like nuts and bold's here stock bolds are metric.
magnet wire in the US is all in #AWG where we have it in metric
And when we calculate a coil we use metric formula's :-) and electricians tend to use different formula's then electric engineers. This stuff divides by bureaucratic force to some extend. Best would be to use either and do away with the BS, but that's no option.
Over here Imperial materials, bolds, pipes etc are generally more expensive and harder to get hold of in the average hardware store. The trick will be to figure out ways to be flexible enough to cater for all. so that the same thing can be build in India or Australia or Japan (dare I say Russia? :-D) with whatever is cheapest or most easy to source over there.

It's just something to keep in mind from the very start and come up with options along the way.