[DanBC]

Why do people use it then? Specifically, why is it used in the original image?

They must think it does something? Or are people just following procedures?

[iand]

They are claiming ownership over the mark, but haven't registered it. It has less legal force but still counts for a trademark infringement.

[pwaring]

It suggests that the company has some rights to the brand and might act as a deterrent to others using the brand without permission (especially as most people probably don't understand the difference between registered and unregistered marks).