[ketralnis]

I don't know why it's named that way but you need some number of cross-country flights and hours because there are skills that you pick up doing that (several kinds of navigation, fuel management, weather management, flight planning, map reading, etc) that you wouldn't by flying in circles or by spending time in the pattern (looped takeoffs and landings, which you do also need to do a fair amount of but builds a separate set of skills)

[shkkmo]

"cross-country" has a similar meaning in many contexts, skiing, biking, planes, running, etc. I believe it was originally coined in running and then extended to other pursuits. The 'country' part of the term comes from the sense that means "non-urban land" rather than "geopolitical state".