Incandescent bulbs Can and do start fires as well. Many barns have burned down from fires started by bare 100 watt incandescent bulbs.
Also, “explosion proof” enclosures for incandescent bulbs are required in certain industrial locations.
Some of the problems come from the bulbs getting damaged, then failing and starting fires, but not all.
The ballast in standard fluorescent fixtures can cause fires as well.
The biggest fire danger with the CF bulbs are installing them in dimmer equipped circuits, this greatly increases the danger of fire unless special “dimmer compatable” CFLs are used.
A barn fire is far more likely to be spontaneous combustion OR caused by the wiring going too the 100 watt bulb. Barns are not known for safe wiring practices. Put the bulb up where it can't be hit and it's safe. BTW I just placed a thermometer on the 100 watt bulb in my hall. It reached about 195 degrees surface temp. A 60 watt bulb I can unscrew one hot with my bare hands.
The ballast in standard fluorescent fixtures can cause fires as well.
Generally they make smoke & thats it. We even used them onboard ship. A ballast in that case is a simple step up transformer. The difference is it has a lot more room too displace heat. Such a ballast usually gives you ample warning it is going bad also.