but surely they wouldn't punish this six-Mac, three iPod and one iPhone household
It has nothing to do with punishment or Apple not wanting you to do it.
It has to do with copyrights and who (which company/music label/movie house) has what rights to sell items in a specific country.
An item might be licensed in one country by Label A but licensed in another country by label B.
If/when the entertainment industry gets its act together and understands there are very few individual markets anymore (due to the internet), perhaps it will get cleaned up.
Until then, companies that sell these items are obliged to live by the rules and at a minimum, Apple feels confident the way they handle it meets the intent.