The thing with velomobiles and recumbent trikes is, yes, there's a visibility issue due to them being low, and traffic not having much of a chance to see you in certain situations. Those situations are usually parking lots.

But, as soon as other traffic has a chance to see you, especially if you're in a velomobile, they will notice you unless they're so oblivious that they wouldn't notice a naked clown dancing in the street. That's how much they stand out.