I'd like to add my own persective as a full-time traffic reporter in NYC for the past 13 years.
Previously I was the afternoon driver for an oldies am/fm combo (WNNJ, Newton NJ). One day we showed up to find the owners had replaced all us live dj's with the Jones service (they then later sold to Nassau...which sold to CC).
Desperate for work, I shopped my T&A everywhere. A guy I knew from an even earlier gig, who then went on to Shadow Traffic, suggested I apply there. I didn't want to, as I'd always considered it a place for jocks who weren't good enough to actually host a show. But I had bills to pay, so.....
I'm glad I did. They took me on after a tryout and an (unpaid) month long training session. After that though, the perks became very evident. It's an AFTRA gig, so in addition to making 3 times as much money as my old job, we also get medical, dental, guaranteed annual raises and are vested in a retirement fund.
Aside from that obvious financial boon, there is also a less obvious one: relative job security. Shadow Traffic, where I work, is never going to flip format. Similarly, I don't have to worry that my station's book looks lousy this quarter, and will the GM decide to bring in a new team to rectify that. Unless I really screw up to the point where major subscriber stations decide they don't want me on their airwaves, I've got a job.
I grant you, it's not as ego-stroking as jocking my own show. But I've been able to buy a nice house, a couple of cars, keep up my hobby of racing motorcycles, get married, and pack my fridge with micro-brews for almost a decade and a half now without worrying about showing up to work one morning and finding my station has just been sold to Jones again and I'm out on the street. That means more and more to me, the longer I'm in this business.
And just personally, I actually do enjoy the work. Here in the NYC market, there is traffic all the time so the days fly by. It's always busy, there's always something to talk about, and you know that (especially during drive time) tons of people are listening to you. Plus, you get to be on a lot of stations (I'm on 11 every day) and many of them make you part of the show. You really get to show your chops to diverse audiences in several formats. I'm lucky that I'm part of the morning team on WOR, as heavily promoted as the hosts, and am now even more recognizable than when I had my own show at a smaller station. I even get mobbed at their remotes, just like the two hosts - and sometimes their remotes are in great locations, like Ireland for St. Patty's Day! It's weird actually, but...I have to say, I love it
So hopefully that answers your question a bit, as to why some announcers don't mind staying "mere traffic reporters" their entire carreer.
Tom