In terms of the USA, I believe you'll find that tandem riding is quite popular, with a number of firms making reasonable numbers of expensive, advanced units that perform flawlessly. As you would expect, there are listservs (tandem@hobbs), specialist shops, and many weekend tandem rallies - Susan and I helped to organize two of them a long time ago.
But, the Q. here is why so few folks seem to have a lot of interest in vintage-period tandems. There the answers are much more nuanced, I think. First, they take a huge amount of space. Second, they require commitment by both haves of the couple if they are going to be a part of an "active" ownership, and ridden. And most of the vintage tandems have very short stoker (rear rider) sections, and are thus downright unpleasant to ride far if you're not really into that sort of thing. Finally, it wasn't until Santana grabbed the output of the mountain bike craze that we started seeing tandems that could be taken out of the box and just ridden. Prior to that, every owner had to be hot-rodder and mechanic, too: the stuff available just wasn't up to snuff for the task. When we started going to tandem rallies in the late 70s, one of the "prizes" awarded was always the Broken Spoke award, for the pair with the worst mechanical misfortunes over the weekend.
Susan and I have had at least one tandem for over 40 years. Much as I admire the old Taylors and others (and I even got to work on a Rene Herse now owned by a CR member), I have no plans to acquire another vintage tandem, ever.
harvey sachs mcLean va. ++++++++++++++++++++++++++++++++++++++++++++++++++ Alex March asks: Looking through period photos and magazines, and as a Rene Herse Alex Singer etc collector, I notice that tandems were really popular in the 50s and 60s in France. Always husband in front, wife behind. Sometimes a little trailer behind for the offspring.
Why is it you never see a tandem on the road nowadays?
Something to do with people being more individualistic? Or women's liberation? The radical decrease in the number of tandems produced and ridden must say something about the history of social relations.
Are there any tandem riders on the CR list? Peter (Weigle), have you ever made a tandem?