Process serving is not a very well known profession to the general public.  Anything having to do with the law tends to be misunderstood and not trusted.  If you mention that you are a process server, you will probably get blank stares.  Either that or you might have someone back away from you a step or two.

There is an old tradition of shooting the messenger when the messenger has to bring bad news.  At least now we don't get our heads chopped off literally when we serve someone court papers, but sometimes we get it chopped off metaphorically.