How can you compare two wars 80 years apart given the advancements in nearly every area. Polish soldiers couldn't watch German soldiers moving around from the s

How can you compare two wars 80 years apart given the advancements in nearly every area. Polish soldiers couldn't watch German soldiers moving around from the safety of a bunker via a phone screen. The available, basic intelligence alone could keep a war like this going for months. It's why I don't understand how it's happened. Wars like this - between modern countries - just should not exist as a matter of common sense (e.g. Mutual destruction theory).