Haha, well, I've never heard of anyone being treated horribly or arrested(!) for
overdue items, but it is the responsiblity of the patron to be aware of when their items are due. The items can always be renewed (even online!), or even re-checked out, that is, if someone else hasn't requested a hold on the item. Several notices are mailed out informing the patron that the item is overdue. Often, if the fine remains under a certain amount, it will eventually be waived. There are also good and legit excuses some patrons have for not returning books on time -- such as being in a hospital -- and surely fines would be waived in such circumstances. However, if someone has an item that's been overdue for a year and they've accumulated over a hundred dollars in fees, well, they need to be more responsible, dontcha think?
It's important to remember that librarians need to protect their resources so that other patrons are able to use the materials, as well. Libraries function on a budget, and unfortunately too many people abuse their libraries by stealing items, vandalizing, losing materials, and/or never returning materials. How is that fair to others in the community who need such resources?
It is as such that fines are a necessary evil. (Otherwise, how else can libraries ensure they can get their materials back?)