AI in singleplayer games is completely broken and passive. You can take on 4 absurd AIs and they are just passive with very few attacks.
The game was broken in this way ever since Dominion was added.
I understand that the main focus is multiplayer, but it’s insane that we don’t have a fix for something so basic and at the core of the game. Please fix this.
Yea 
Unfortunately, that’s true.
Yeah, AI is not even good for practice a build order. It is by far the worst Age of Empires AI. The only way to make it better is to play the highest lv AI, which has an extreme economy buff that allows it to spam tons of units, but there is no strategy, there is no micro, there is no response to your units, there is nothing. It is just like playing against an infinite soldiers producer, which is not even fun or usefull to get some practice.
I find that it varies a lot. Some games the AI basically does nothing, but then the next game it goes nuts and spams an insane amount of units even earlygame.