It is entirely possible I am wrong as I have only seen Brown and Grizzly bears, I will take a look into it further thanks.
You're not wrong, it isn't natural behaviour at all.
Zoo animals often do get used to the presence of visitors (something Frontier has failed to understand with the constant "animal is stressed" issue in many species in-game) and might interact with the public on a basic level (there is some research to suggest that interaction between great apes and zoo guests through glass is a good source of enrichment in zoos, too), but bears do not 'wave'.
One thing that a lot of zoos do these days is stress the importance of not 'anthropomorphising' animal behaviours. That is to say, it's dangerous to assume an animal is behaving a certain way for the same reason a human is. Great apes are another great example of this; in most primates, baring teeth is a sign of aggression and fears, yet people often say, "Oh, look, the monkey's smiling at me!" It's anti-educational and therefore anti-conservational. If the bear is raising its paw, it's either trained behaviour and the bear expects a reward (extremely likely in the posted example), or it's a bear-specific behaviour that has nothing to do with whatever the humans viewing it think it does.
In any case, implementing some kind of guest/animal interaction in the game seems counterproductive to creating a realistic zoo environment. Some zoos do it under special circumtances (my local lets you hand-feed the giraffes - but only at specific times of day, and only using food provided by the keepers themselves), which is a system I wouldn't be opposed to seeing in-game, but the general rule of thumb for any zoo is to create an environment that is as "hands-off" as possible. The goal is to encourage animals to behave as naturally as possible (given the circumstances) and telling people it's okay to go into the tortoise enclosure and manhandle the tortoises for a cute photo-op isn't something a zoo would do willy-nilly.
