The NYFD had allowed members to carry and use bail out rigs,then they came out with an order outlawing the use of the Bail out rigs,now after the incident talked about above they reinstituted the use of such rigs.
When your entry/escape route to the exit,stairway are cut off you clip into the building area between two windows or clip into a secured,hopefully secured object,like a radiator or if you make it to a roof you anchor around an object like the railings of a syatirway,or around a structure on the roof.
Now many men and many departments have repel harnesses on their turn out gear.
I was trapped and burned in my first job and never went to a job after that without my own clip,harness and line.
Then the department made the harness and rope mandatory.
With parachuting the reserve was used as the lowering line if low enough,I also carried a length of line in my cargo pocket for getting down from a tree,just in case we were dropped away from the DZ,which rarely happens,LOL.
I have trained regularly in use of the bail out bag and the regular roof repel bag on the departments and been trained in self repel and being lowered from the roof to pick up people stuck in windows at jobs.
I have never had to be lowered and make a rescue at a fire but many have ,NYC did one just the other day and they have made many news worthy rope rescues.
I have used fast roping,STABO and SPIE rigging and the penetrator/extractor in the miliatry.
I have used climbing and repel lines and harnesses in rock climbing
My local Police Department ESU trains and uses repel rigs in multy story building Hostage rescue and barricaded individual,it is used as an outside platform to break windows,throw in Flash Bangs and CS.
Some NYC department medics wear or carry rigs as well.
How much it is actually used is hard to say,but for me ,having been trapped in a Backdraft,if I had to have it and use it only once,it is way better than being on fire and having to think of jumping from an upper floor with nothing but the hope I make a good PLF and live.lol.
Look at 9/11 and the Trade Center,those people knew they would not live and they willing jumped to certain death,so I would rather be prepared than make that choice.
Outside of the military,Police ,fire, some EMS/Medics and rock climbers I doubt Repel and or Bail out bags are used much.