"E2E teams" are difficult because your success depends on specialized teams to not screw you over - and not just in terms of politics, but it can happen just from them protecting their codebases and trying to focus on delivering under the pressure they're getting from their management, independently of the "E2E team's" goals.

If you think about the people in your team who command the respect and trust to be able to get past all of that wariness of team outsiders, it's usually a really small number of people, and usually they are veterans who've been around for long enough to have built those relationships.