[Kunst]

possibly due to significant higher familiarity between the versions of English? That said, we do often get edits to replace cameos with local celebs.

You do get a lot of "American dubbing" on cartoons, so that's why I guess they don't bother

Plus, of course they can easily export to pretty much anywhere else in the world.
Plus x2, the Estuary English accents (often used in English dubs) have at times some "negative connotations" even inside of the UK, maybe? Although by now cartoon dubs also have an array of regional accents, often not the thick ones of course

American English in the media has little accent variation (in real life it does, of course) and is seen as an "international form of English" because of the US power itself.
So, more marketable, easier to export, even somehow accepted in the UK, and, the way I see it, it kind of is a "status quo", so they don't have to use an array of British regional accents (more expensive) not to spark controversy?

The "two Spanish dubs" situation is different as (I naturally understand a lot of Spanish) the two realities (Latin America and Spain) don't have a lot of contact one with the other.
E.G. Spaniards (wrongly) think the LA Spanish accent (the "pan-LA" standard used in pan-LA dubbing and productions) sounds wrong or funny (although easy to understand), while, viceversa, Latin Americans think Spaniards speak "strange", with a lisp (because they use the "th" sound, which for them is alien).

Unlike British and American English, where the two forms of English are both seen as just two natural variants