you can take pictures of anybody, and even publish and sell without the need of a model release form.
if this wasn't true, then the paparazzo could not exist.
the only time you need a model release form is for advertising a product or election campaigns etc etc.
The paparazzo thing is based on the person being of "public interest", which is an exclusion to the right of controlling the publishing of ones image.
At least within german legislature, and seemnigly elsewhere.