There's lots of things you can do in the current model of D&D that doesn't require a die roll. You can jump a set amount based on your Strength, with an optional roll if the DM wishes to allow you to jump more.
You can climb or swim automatically, unless the DM rules there are few handholds or the water is especially rough. In most other systems, you'd have to roll to perform any of these feats.
Casting a spell doesn't require a roll in most cases (but sometimes it does), but neither does parrying via the Defensive Duelist Feat.
I could go on, but the absence or presence of a die roll doesn't mean something it trivially simple- it just means that the designers of the system felt that some things should be allowed to happen, to keep the game running smoothly.