This tutorial – https://fritzing.org/learning/tutorials/designing-pcb/ – says that you can use Fritzing for single-sided PCBs, but there is a “copper top” and “copper bottom” layer in the app. So is this just a typo?
No. You can select single sided in Inspector.
selecting single sided here will make a single sided board.
But the language makes no mention of double-sided boards – it sounds like you can only make single-sided boards. I think they need to say that you can “use Fritzing for single- and double-sided PCBs.”