That’s because enforcement is an interpretation of scope
Ralston 7, Registered Patent Attorney and Associate with Thorpe North and Western, LLP in Sandy, UT; Juris Doctor University of Utah (2005), Doctor of Engineering, University of Massachusetts-Lowell (1993), M.S. University of Southern California (1984), B.S. Massachusetts Institute of Technology (1982). (William T., Spring 2007, “ARTICLE: Foreign Equivalents of the U.S. Doctrine of Equivalents: We're Playing in the Same Key But It's Not Quite Harmony”, 6 Chi.-Kent J. Intell. Prop. 177, 178. Lexis accessed online via KU libraries)
Various treaties have streamlined the process by which patents are obtained in multiple countries. 11 In contrast, patent enforcement, and thus interpretation of patent scope, is based in national law. 12 Because national law can differ between countries, the scope of patent protection provided by an international patent application may therefore vary widely from country to country. The Epilady cases 13 are a particularly poignant example, as different jurisdictions arrived at different outcomes in the same patent infringement dispute. 14