Someone else, I forget who, said something clever on this matter. I will paraphrase:
Because they are not ACTUALLY zombies. They are not ACTUALLY undead, "Zombie" is just the name of the Talent. Just like taking the Demon Talent does not make your eyes glow and scales punch out of your back, or the Ice King Talent does not make a crown of ice appear on your head.
I think it's me you're paraphrasing! Hello!
As for Sunlight - I personally hopet hat the undead PCs don't have the zombie talent and don't bleed poison unless they want to. Some of the undead / skeletons in game already don't have the healed by poison thing, though I do believe they do get benefits from cursed surfaces and messed up by blessed (Which is already gonna make things hard enough.)
