Many students with academic and athletic scholarships can attend college and never incur any student debt. Also, a student whose parents are very well off and pay for their whole tuition cost would also not incur any debt. A student who receives financial aid and goes to a community college or other low costing college, could potentially avoid student debt if they took only a couple classes at a time, therefore keeping the cost down.
I was lucky enough that my family had a college fund for me. However, there are plenty of people who don't have that luxury. There are government aid options and scholarships, but often times, they are very those with almost no money to their name. For the average middle class student, financial aid will look over you, even if you can't afford college.