The pack behavior system only really applies to animals with distinct leadership roles. Lions don't really have this. True, lion prides only tolerate one or two males, but they don't lead the pride. That's purely an artifact of hoarding mating rights to the group of females. Lion prides are more akin to like, a herd of horses than a pack of wolves in that regard.
This has very little to do with the question. The player is asking about animal interactions within their unit (pride) obviously not a pack or herd, but this is absolutely irrelevant for the context of the question. There should be greater interaction in the game between animals within the same unit as long as this behavior mimics to some extend what occurs in zoos. The game is a zoo simulation, so the behaviors reflected in the mechanics of the game should somewhat mirror what you would normally find in captivity.
Male lions do exhibit a high level of interaction with each other in captivity, lionesses while not as engaged as their male counterparts, will still have a higher level of interaction that what is currently shown in the game. I believe that the cue taken for the devs when it comes to their behavior might originate from the notion that lions spent most of their time in captivity pacing and sleeping, but in a game you definitely would want to showcase those interactions as well.
The animal life cycle in PZ makes it difficult for certain behaviors to be reasonably visible, however I do not think that the current limitations in animal group interactions are because of this, my take is that it all correlates to the complexity of the AI system and how much this takes out of operating systems. I'm not completely sure that an increment in complex or even moderate AI behavior interactions would be handled by most player systems.
In short the lack of group interactions between lions and all other animals in the game has nothing to do with real life accurate or inaccurate depictions, it all boils down to technological limitations.
