If you separate performance luxury cars from that description - as many of those could have likely had manual trans, i.e. big AMG Mercs or TOTL BMW's, exotics like Ferrari etc. - I would guess that is the case.
Gas has always been more expensive there, and the manual trans is more efficient (still today, in fact manual is making a mini-comeback lately). Also engine sizes were often smaller (still are) because of that cost & also taxes imposed on larger displacement engines, and the stick is a better way to squeeze the best performance out of a smaller engine. Manual trans were also less expensive, able to last relatively longer with lower cost maintenance (look at cost to replace a clutch & throwout bearing vs. rebuilding a 4- or 5-spd automatic), and so forth. For the performance cars, sometimes it was a decision based on what was available to handle that much HP and torque as well as whether the car was built to drive the wheels off as opposed to being a luxury cruiser.
Again, this is me speaking in generalities and without having lived there, though I did spend many years working on & around European cars here in the US. Take all of that with a grain of salt, and ymmv basically.
John
P.S. Also have to keep it in context of time; floppy paddle sequential gearboxes filled the space on some TOTL luxury or performance luxury cars more recently.