That's because of how the mainstream media labels Bitcoin as THE currency to conduct transactions anonymously. In most cases it's accompanied by a lengthy article where they explain that criminals have used Bitcoin either to launder money or buy drugs and whatnot. If criminals use Bitcoin, then it surely is anonymous, right?

No one would give a damn if the mainstream media referred to XMR because people don't know what the heck that thing is. Bitcoin is known to most people as household brand.