I have always liked City Living because they did a lot to make the zones feel alive. One of my favorite zone (a zone is the area around your active lot which can have a maximum amount of 20 sims) is the Spice Market, here is a simple picture. Red Squares are where sims are spawning, lines are where they are walking back and forth and circles are where they can hang out doing different things that the game tells them to.
https://i.imgur.com/w6TOGwT.png
In this zone we have sims walking back and forth between the center, sims playing basketball, children playing, teenagers watching the art, market stands where sims buy food, artists performing, and they also move around so they are not standing at the same spot, demonstrations, weirdos rummaging the trash, sims doing maintenance, sims sitting at park benches, tourists walking around and the whole zone also changes when a festival is happening.
There are also cars and trains going back and forth, and low poly sims walking outside the area so that the city feels crowded.
The market in that we saw in Snowy Escape looked completely empty and deserted because it had none of these things... I could see one npc role, Yamachan, and also maybe one market stand. The zone is so huge and just full of decor buildings in the middle and empty streets with very few sims walking around.
