Why do some open world games have minimal or no loading screens while others are heavily invested in them as the player moves from one area to another?
Often, loading screens in open world games are because of technical limitations. A combination of not enough world assets can be stored in memory, and data can’t be streamed from the disc/cartridge/hard drive fast enough to allow seamless loading. Which also depends on how much detail there is in the game world (3D models and textures), and how fast the player character can move inside it. And that will be a combination of actual hardware limitations, and software (lazy coding or not enough time/budget). Even if you don’t have the technical limitations, it takes effort to make a game engine that can seamlessly load the environment as you move through it, and not every developer has the resources or expertise for that.
Sometimes loading screens are hidden from the player. If you’re stuck in an elevator or corridor, the player character is limited to a slow movement speed or specific animation, or the camera is fixed in a particular position, chances are it’s because the next map section is being loaded.
Other times, loading screens are deliberately programmed in, even when not technically needed, because they’re easy ways to clear up the game state (game objects out of place, NPC scripts or other triggers not loaded properly etc).
See also [https://www.gamesradar.com/au/the-secret-art-of-the-video-game-loading-screen-and-why-they-wont-be-going-away-anytime-soon/](https://www.gamesradar.com/au/the-secret-art-of-the-video-game-loading-screen-and-why-they-wont-be-going-away-anytime-soon/)
It’s a choice by the game company. There are ways to load the next area while you’re still playing, but doing this is often technically complicated and requires additional time and therefore money. It’s easier to just show a loading screen.
Games that invest in smarter loading often do it because it’s a key part of the user experience they want. Other games would prefer to spend that effort on other features and content.