Most students avoid or minimize prep for classes. If they say they don't have the time, then they don't want to. Thats the oldest excuse in the world. When my students didn't prepare, I wrote a 1 page concise summary of the lesson and handed it out. It's extra work and they were appreciative.
As the poster said, have a easy quiz every other day, first thing. If the students came late, they missed it! If they did not prep or read the chapter, the quiz shows this. this is much more work for you, and I never did it. Or from your syllabus, state that you will deduct points in the grade for lack of preparation.