All auto manufacturers selling vehicles in USA are policed and must meet the Federal Motor Carrier Safety Administration, FMCSA regulations.
Windshield Wipers and Washing System
Vehicles must be equipped with a power-driven windshield wiping system, according to FMCSA. The wiping system must have two speed frequencies and one frequency must reach a speed of 45 cycles per minute according to FMCSA regulations. The other frequency needs to have a variance in speed by at least 15 cycles per minute either faster or slower than 45 cycles per minute without going slower than 20 cycles per minute. The washing system must meet the requirements of SAE International for vehicles that weigh less than 10,000 lb.
plus
Wiped area.
When tested wet in accordance with SAE Recommended Practice J903a, May 1966, each passenger car windshield wiping system shall wipe the percentage of Areas A, B, and C of the windshield (established in accordance with S4.1.2.1) that (1) is specified in column 2 of the applicable table following subparagraph S4.1.2.1 and (2) is within the area bounded by a perimeter line on the glazing surface 25 millimeters from the edge of the daylight opening.
http://www.fmcsa.dot.gov/rules-regulations/administration/fmcsr/fmcsrruletext.aspx?reg=571.104
I think Ford used this specific windscreen wiper function/path on the new Focus so they did not have to have two different set ups to meet the USA regulations. Lots of extra cost incurred if two systems are needed.
Ever notice on the USA Fiesta how the front passenger side wiper parks in an upward angle on the windscreen, whereas the rest of the world Fiesta right side wipe parks in the normal spot, on the lower edge of the windscreen.
Good old USA wiper regulations forced Ford to redesign the wiper functionality as the Fiesta was not originally planned for North American consumption.