Why is it that 9 times out of 10 the backing vocalists in songs are older than the lead vocalists? E.g. Niki Harris (born 1962) as backing vocalist for LeAnn Rimes (born 1982) in Can't Fight the Moonlight?
It just seems somewhat weird that backing vocalists are mostly if not always older than their lead vocalists.
Backing vocalists neither have to overly cater to the "young and sexy" optics, nor do they have to provide a cutting voice for dramatic effect. As a consequence, their voice, control, and musicality tends to gain quality over much of their professional career.
The identity of the act is not tailored to them so they can just move between productions and there is no necessity to shelve them when promoting newer acts (where not much but the front row faces and legs are new) in order to generate new sales.
Job dynamics are quite different for male singers once you leave the boygroup acts. They tend to have less of a turnover as well as less of a market. You'll find that their front/background age dynamic is much less pronounced in the direction you describe than with female singers.
So far, I'd agree pretty much with all the existing 4 answers, so in the hopes of providing something new...
Backing vocalists, the good ones, have a career as a backing vocalist.
They will be working long, long after most of the acts they were booked to record/tour with have got their 5th gold star at the "Would you like fries with that?" establishment of your choice.
Very very few acts have an extended career.
Very very few backing vocalists are recognisable to the general public. Some of them quite like it that way. They do their job, they tour the world, or get to work in the coolest studios with a lot of current 'famous names'.
They'll still be doing that next year... & the year after... & the year after.
Some of them will have started out as 'young hopefuls', trying to carve their own path in the industry, but never quite made it. Others will have decided that's what they'd rather do in the first place.
Some go on to other things in the industry - a friend of mine, after first working as a member of a band with a couple of minor hits, then did BVs when a famous 80's band played in China as part of their world tour. She subsequently became a radio DJ, raised a family & generally enjoyed the whole thing.
Another friend, whom I first met in the early 80's, is still doing it. Power to her :)
Another friend decided she'd had enough after 6 or 7 years & went back to a "normal" life. She prefers that in her 50s she's not on the road all the time, nor in the studio til 4am.
I, on the other hand [echoing what user2842 said] had a couple of years at it when I was young... til the phone stopped ringing - as they say, it's different for girls ;-)
I can't say definitively, but it may just be a simple issue of visual aesthetics: if you want to sell more albums, you'll probably have better luck with the 20-something blond standing in front.
In the specific case of Niki Harris, it may also have been to give a little star-power to the up and comer. Harris worked pretty extensively with Madonna, so her experiences could have been sought out to help the up-and-coming LeAnn Rimes.
Often, backing vocalists work in twos, threes or fours. As such, their timing and ability to keep good harmony is important. This is down to a lot of experience singing in that sort of situation, which the younger pop stars don't usually have. A young singer sometimes finds it hard to be part of a vocal ensemble, being used to singing solo. There's obviously, as already mentioned, the physical appeal, and as backing singers, there's not so much importance put on looking young and appealing.
