if they don't show up to class they get punished by not learning enough and subsequently failing their exams/assessments

My (UK) University was very clear that attendance was not mandatory, but if you weren't attending lectures you were not going to get any extra help from the lecturers etc

I don't think that's an unreasonable position to take, but it's nice if you _know_ rather than _guess_ who bothered to make it in to class.