My partner at work actually comes right out and says "Why should I? You're here and I can use yours!" I asked him what he did before I was hired and he told me that he's got a 2D MAG in the truck if he really needs it.
I just don't see why it's so inconvenient to carry a small light, especially when your job constantly puts you in situations where you need to see into dark holes, steam tunnels, attics, crawl spaces, ceilings, etc.
There's nothing worse than crawling down a steam tunnel (think hot steam lines, low hanging pipes, puddles of water, electrical wires everywhere, Black Widow spiders and maybe...just maybe...Freddy Kruger!
) and having what sparce AC lighting there is down there, go out on you! I don't know about all of you (actually I do, LOL!), but "feeling" my way down a 200' steam tunnel with no light at all, isn't high on my "fun things to do" list!
To each his own, I guess.