It's okay if the ESA operates separately and independently. And it's okay if the europeans don't want to deal with complex American security law, despite a 500 page EU constitution that deals with the tiniest of details, which gives such a document less of a driving spirit but more of a tedious hurdle.
Science benefits from cooperation and it also benefits from redundant, parallel independent efforts.
Nothing like starting from a clean slate is just as good as not having to re-invent the wheel. Both have their benefits.