It did when I was a poor college student who worked higher paying jobs to ensure I had enough money to continue college (not to repay debt...but to buy beans and rice during the semester.)
Now that I have worked in a number of animal fields and hired a variety of interns, I completly understand. So, from the other side of the internship fence:
1) the simple economics of animal related fields enabled internships to avoid paying interns. The demand is simply higher at $0 than I can fill. So, why should I pay money to someone when I can have another person do it for free? Especially when I have thousands of other uses for that money?
2) of all the zoos in North America, only 5 were self-supporting in 2005. That means those larger zoos have to justify even a living stipend to various boards, committees and government officials, not to mention tax payers. Some of the self supporting zoos actually CHARGE for the more desirable unpaid internships.
3) the money that is used to pay an intern rarely recompensates itself. It rarely generates long term benefit to the organization. If you want a paid internship, you need to bring something amazing to the table which will either provide long term benefit, reduce costs, or increase revenue. Simple as that.
4)most interns are working for the experience they gained...paid internships are rare, generaly go to individuals who already did an unpaid, and who come to the internship with all the necessary skills in place...those skills that most interns are interning to learn.
5) interns generally cost money, even if they are unpaid. They must be supervised, liability insurance must be carried to cover them (sometimes additional riders), and they must be trained. If I have a group of interns with volunteers, I generally need to pay someone just to supervise them....meaning I won't pay them.
OK, so the basics behind us, I generally hired 4-16 unpaid interns over the year, most during the summer. I also hired 1-2 paid interns, 4-6 paid counselors for camp, 1 paid receptionist, 4-6 paid camp assistants, and 2 paid keepers/presesnters.
The most important people in that list were my keepers, follwed by my receptionist, then essentially everyone else. Unpaid interns were generally college students or adults who wanted to get thier foot in the door for employment. Rarely did they know how to work with exotics, and generally their skills around volunteers, safety systems, customers, etc were unknown. I typically maintained a list of projects that various departments wanted labor for that were more involved than we were willing to ask a volunteer to do, but not so involved that they needed specialized skills. Perhaps this was refurbishing an exhibit or helping in recovery (scouring clean) a building. During the summer, our kitchen staff often had an intern to assist with diet changes, behavioral enrichment, etc.
From those unpaid interns that reapplied next summer, I would have noted who worked well with staff, volunteers, customers, animals, etc. I would have also noted who showed up late, took the lead, was safety conscious, generated usable ideas, didn't complain, etc. I kept lists of ideas people had come up with the previous season....I would examine that and see if anything fit our zoo's needs. If it did, and the applicant had the skills and was exceptional, I might offer them a paid internship. Then there was a return in the outlay of money.
The only other times I offered paid internships involved individuals who came in and diagramed something impressive that would benefit us. We had an intern that put together a Teddy Bear Fair in November, a traditionally slow time (sociology student interested in early education). One who rebuilt our boat docks (which needed replacing) for less than we had planned to spend (engineer.) Another who stabilized the banks in our lagoon and left us with a 5 year plan to replace lost earth (enviro scientist.) Another that helped us move half the zoo onto carcass feeding (animal sci/nutrition.) The one I remember most is the person that helped install pathways in water prone areas that were a polymer mix of some sort, opening a new area of our zoo for exhibition.
As you can see, most of these individuals contributed to the zoo itself in a big way, which enabled me to justify paying them. All of those contributions were long term, resulting in multiple years of benefit. Also, they generally involved skills the individual brought to the table that were outside of the animal field, or were highly specialized within the field. The nutrition intern actually had a PhD in the field reviewing the diets she put together (a huge resource for us for free.) Typically, they weren't learning about the animals/husbandry/handling/etc as much as they were learning about project management, volunteer management, budgetting, timelines, etc.
Just thought I would share some views from the other side.
) However, if I want to not have outstanding loans from undergrad, I have to make some sort of money over summers. Or at least break even. In addition, the 2k figure was definitely not meant to be per month- I was just pulling a number out of the air to demonstrate paying for purely transportation/housing/food. 
