They're not, they just fucked around or prioritised other things thinking that they could coast by on the same formula that Witcher 3 had. The thing is that the diorama works fine in Witcher 3 because the player has no expectation of how a dark fantasy village should work as a sandbox. It's just a bunch of small village people milling about. Works fine. More or less the same for the medieval city too. The shallowness of the world doesn't hurt it.

A modern setting though? And with expectations of the genre? You can't claim to be making AAA and then not really meet the standards that even small studios have met.