Engines just don't have the concept of "allowing an opponent the biggest chance to screw up". They follow blindly their evaluation function. In an endgame, the evaluation tells it that M5 is better than M2. In an opening with piece odds, the evaluation tells it that -3 is better than -3.5. When playing with piece odds against a human, an engine doesn't win because it tricks the human into difficult positions; it wins because the human (any human) is very likely to screw up in any position. But if you match an engine with piece odds against a similar engine, you will start to see those "random" moves too.