What makes 20th century modern poetry "difficult" and what are some different types of difficulty?

Excerpt from the trip of a lifetime elizabeth mohn 3 a little more than a week ago, my mother and father started packing our suitcases to prepare for our trip. my entire family woke up early sunday morning, packed the car, and began our expedition to niagara falls. when we reached the american-canadian border, i was excited to enter a foreign country for the first time. the third paragraph is mainly about a) traveling to niagara falls b) leaving the hotel. c) seeing the falls. d) returning home.