Most authors of niche or custom software either don't care about native look and feel (making application with modules written in C with Motif, Qt, MFC, Tcl/Tk, Java and two or so custom languages look seamless is colossal waste of time and that kind of construction seems to be common for most niche things I've seen) or actively make their applications look non-native (Even Microsoft's ERP solutions have decidedly non-native feel to them).
