PHP has accomplished code reuse on the app level: applications like Wordpress and Drupal are world class and you just can't find installable web apps in other languages that have reached anywhere near the level of success. Occasionally you find an app in another language and generally it doesn't have the fit-and-finish that the successful PHP apps have.
Other languages, on the other hand, grow frameworks like cancer cells, and I wonder what disease they have that prevents these frameworks from being actually usable to build apps.