Because people are daft and want their outside areas lit up to clear summers day levels. Which means that for security purposes they are hopeless as any semblance of night vision is destroyed and they cannot see anything beyound the pool of blinding light.
CFLs vary some come on very dim when cold (as in outside winter zero or below cold) others are much better. Most of the outside lights here have
60W GLS bulbs, enough light to see by and not so much as to make anything outside the immediate area just black. One is CFL but that is used a lot, the others might get a days use/year...