UK and Sweden have both pledged to Ecuador since at least 2012 that neither of them would extradite Assange to a death-penalty country or a country where he might be tortured (including even the mildest levels of torture, stuff like leaving lights on during sleep periods or playing loud music at all hours).

So this is longstanding policy for both Britain and Sweden and it applies to all persons, not just Assange. And to all countries with the death penalty, not just America.