Wilier Zero 7; Merlin Extralight; Co-Motion Robusta; Schwinn Paramount; Motobecane Phantom Cross; Cervelo P2; Motebecane Ti Fly 29er; Calfee Dragonfly Tandem
The original hub on our Burley Duet didn't have QR. Mostly a cost issue.
Also a durability issue. If it's the same era as ours (1994) it had a freewheel instead of a cassette. A tandem hub with a freewheel is more prone to break an axel than a freehub with a cassette, due to the spacing of the bearings. And make the axel hollow for the QR and it get's worse, particularly if its not a high quality (i.e expensive hub.)
We eventually replaced ours with a cassette hub, after breaking an axel.
And if you ride farther than you're willing to walk you do need to carry a 15mm wrench, or a small adjutable wrench. We used the original Cool Tool,and it worked well.
Agree, older Duets did not have QR on rear wheel. Whether you are on tour or not, you need to carry the appropriate tool to remove axle nuts in case of a rear flat or other wheel issues.
'Be Prepared . . . 'old Boyscout motto!