If the student wants to waist their money by not attending, let them. They are adults.
If the student has something truly more important to do at that time, don't punish them.
If the professor's ego is so big that he has to demand the captive audience but is to lazy to take attendance, fire him/her.
How lazy can we get as a species?
Anecdotal evidence of a good professor, In a 400 level (senior) engineering class I had a professor that stopped one student from waking another student who had fallen asleep. The professor explained why he didn't mind as he knew his class was not boring and that the student put forth the effort to attend even though it was obvious he was exhausted. That is a good professor, one that can see things from the students point of view. A lot of college students are working thier way though school and realize the value of the education, sometimes they can not make it to class or should not make it to class. College age students are considered adults, treat them as such or they will never act as such.