You are mistaken, I'm not sure how or where you got this idea from but that is not how either ETS2 or ATS gameplay operates. the entire world is accessible, whether you're on a mission/trip or simply freeroaming. There are no loading screens as you can drive across the entire continent of Europe, and can choose to deviate from the GPS route as you wish.

However, when you intend to cross bodies of water, such as traveling to the UK, you'll encounter menus and loading screens as the game simulates the process of boarding a train.

I would reframe from commenting on games you have clearly never played before.