You are extrapolating far too much. The normal titans simply wander in when the wall is breached, seeking humans to kill. The colossal one can kick a gate in and sweep cannons, but that's more or less it, based on what we have seen. It's battery life is also extremely limited. The trap was no trap. Eren was blindly flying forward, paying no attention to his surroundings whatsoever, along a very long road with high visibility. Any random titan would notice him and naturally try to snatch him out of the air. And there were many titans around.
I got a feeling from this episode that Eren is a huge liability. He forgot their whole training the moment he lost his cool and got his whole team annihilated. He's the main character, so he has to survive, and ironically enough it's no doubt only his single-minded and idiotic obsession of killing titans (with his lack of skills but bigger than a titan ego) that will allow him to move forward despite the knowledge he's the reason his team was killed without achieving anything at all. A normal man would be full of regret, but this guy, I reckon, will shrug his shoulders and dream of killing another titan.