Most people can’t. “Read carefully or for comprehension” would probably translate to level 4/5 prose literacy skills in the NCES NAAL (National Center for Education Statistics National Assessment of Adult Literacy). Recent survey puts this group (level 4/5) at 12% of the adult population. Levels 4 and 5 are no longer separated because of the small percentage of people that fall into group 5. Level 4 tasks require you to be able to understand something in the presence of distractors. Just to make up an example, think about the last time you sent an email to someone that had two questions in it. Did they answer both questions? (I’m actually a bit unsure that this falls in level 4.)

(Level 5 includes tasks such as “compare and contrast complex information, or to generate new information making high-level inferences or using specialized background knowledge”.)