Actually, many detected black holes are so called ‘black hole candidates’, which need further precise observation with high resolution.
I think, this explanation is fair enough:
https://esahubble.org/science/black_holes/
‘
Today most astronomers believe that quasars, radio galaxies and the centres of so-called active galaxies just are different views of more or less the same phenomenon: a black hole with energetic jets beaming out from two sides. When the beam is directed towards us we see the bright lighthouse of a quasar. When the orientation of the system is different we observe it as an active galaxy or a radio galaxy. This ‘unified model’ has gained considerable support through a number of Hubble observational programs. The simplistic early ideas have however been replaced by a more complex view of this phenomenon – a view that will continue to evolve in the years to come.’