Yes it's unrealistic because it means extra animation work for the dev team. It also adds nothing to the gameplay. It isn't needed. Do you get upset when other games don't have exactly what was shown in their trailers. This has been an industry standard for decades now, not just in the video game industry either.
I'm going to assume that English isn't your first language, so I'll lay this out in points:
1) Trailer: As I've said twice now, I'm not complaining that it's in the trailer but not in the game. I'm merely pointing out that it actually would be a nice addition to the game to add more life to it. It would add gameplay, as I explain in point 3.
2) Animations: It's not that hard to add new animations to an engine like Cobra. I've been a games developer for 30 years and have used many engines in my time. Just look at games like The Sims, they introduce new animations and interactions all the time, sometimes in expansions and other times in patches. They introduced toddlers to that game as a free update, which required new character models for the toddlers and new interactions for the adult, child and teen sims. They also introduced pools, which required not only adding the pools but also adding swimming animations for the models... So adding 3 people getting out of a jeep and a simple animation to show them working on a fence or filling up a feeder wouldn't be at all hard for FDEV to do.
3) Gameplay: So having your ranger team get out of the vehicle in a carnivore paddock to restock food or repair a fence and then using an ACU to protect them introduces no new gameplay? Surely it adds more gameplay than simply driving up to the item and it magically fixes itself. Currently it's a case of click your fingers and it's fixed, it'd be a lot more engaging and tense if you had to protect them to make sure that a hungry T-rex doesn't have them for lunch.
People are only suggesting additional features because we want to make the game better, which not only improves it for us but you as well. If FDEV weren't interested in adding new features to the game, or listening to feedback, then there wouldn't be a stickied wish list thread at the top of the forum.