Propper random encounters are somewhat of a lost art. The big majority of games released in the last decades don't mention them at all and when they do they don't explain them. And generic random encounter tables for different outdoor environments rarely make much sense either. And those for dungeons are usually generic and not integrated into the background and purpose of the dungeon.
Though admitedly the old D&D editions of the 70s and early 80s didn't do a good job explaining them either. You either follow the rules blindly and discover some interesting things to do with the results over time, or you need someone who already knows them teach it to you.