Crosmando: I've become convinced recently for example that Bethesda's games are actually made on the cheap, this might raise eyebrows but when you think of the amount of bugs and problems they have upon release, and the fact that they have no cinematic cutscenes (the most expensive part of any modern game), as well as other shortcuts (reusing textures, reusing the same voice actor over and over) it really makes sense.
I would guess time is the biggest expense for their games. The use an engine they know and upgrade it only as much as they have to, and they limit expensive assets, but it takes a ton of time to fill such a world. And they are good at making worlds, no matter how disappointing I and other old fans find their more modern stuff.
And pretty much every open world game of that degree has bugs.