I was playing through shadowed paths and noticed that enemy figures are seemingly unaffected by things such as difficult terrain and spiderwebs. Am I missing something or do enemies just have an advantage when it comes to movement?

I believe they are just unaffected.

This seems strange enemies aren't effected by difficult terrain and spider webs. I read through the Shadowed Paths rulebook and the only mention of enemies on terrain was for Elevated Terrain.

So, I guess enemies don't care.