The reason is that if you have any feature on your website that collects email addresses for any reason, you are collecting personally identifiable information. You must provide a way for people to opt of the collection of their information.
These regulations are not in place just to make life hard for small website owners. Place yourself on the other side of the fence for a second and ask yourself if you would appreciate knowing what happens to the information you type into online forms.
The rules and regulations are there to protect consumers, just like you are when you visit other sites.
Website owners should not overlook privacy policies even if they are very small and think they’ll never have a broad audience. There are laws in place concerning the responsibilities of website owners in Europe and many other countries. There are laws being proposed in several states that dictate a number of rules surrounding the collection of personal data belonging to anyone who is a resident of that state, regardless where the website that resident visits is based. In some cases, substantial fines exist or are being proposed.