The electronic cameras were reliable enough, with the big advantage they have over mechanical when shooting kodachrome sold me on them. A mechanical camera will almost never expose slide film correctly.Its not a simple matter of adjusting processing because the exposure will be high in one frame and low the next and theres no prints than can be adjusted, its either right or not.
Bracketing is not an option with action shots, and exposure requirments can change if following a moving object from the start of a pan to the end. It has always cracked me up seeing a motor drive on a FM at the track. Unless they are shooting print film they are wasting film.
The shift away from full mechanical was after people learned the electronic controlled cameras had better exposure control.
I had to laugh in disbelief when I read this. I suppose it all depends on which camera one is talking about. It was in the early 1980s, when camera manufacturers had shifted most of their attention away from mechanical cameras to electronic ones
en masse, when I became interested in photography. My first two cameras were a Canon AE-1 and an A-1. By the time I bought the A-1 I was shooting slides almost exclusively, mostly Kodachrome. And I was
very unhappy with the way many of my slides were turning out. It was the A-1's metering pattern that was the culprit. It was terrible at handling stray light sources that might have been somewhere in the frame, which resulted in severely underexposed slides. Soon after I bought an all-mechanical FTb, and my problems were cured! All because of the difference in metering patterns -- the FTb meters only within a central rectangle that occupies about 12% of the focusing screen. Later I bought a Canon F-1, which uses the same metering pattern as the FTb, and my good luck with shooting slides continued. Soon after buying the F-1, I bought a motor drive for it, and had no difficulties firing off a string of correctly exposed shots as long as the lighting didn't change mid-string -- which happened very seldom. I think you'll find that, in reality, exposure requirements just don't vary that much when you're shooting outdoor subjects -- which is what I've always done using motor drives. And when they do, well, you just have to have your wits about you. Shooting slides takes practice, which it seems most folks can't be bothered with anymore.
I also shoot mechanical Nikons -- F2s mostly, with motor drives more often than not. If you analyze their 60/40 metering patterns, they are almost as knife-edged as the Canons' were, and I've had excellent results shooting slides with them too. Nikon concentrated the pattern to 80/20 with the F3 and I shot many slides with motor drive with the F3, and had no problems.
Oh, and Nikon's FM and FM2/N use Nikon's 60/40 pattern too, so chances are those guys burning through slide film with those cameras were getting well-exposed slides for the most part.
I don't know which type of "track" you're referring to, but I used to be a freelance motorsports photographer and shot slides exclusively at the tracks I went to, and the cameras I was using were the original mechanical Canon F-1s with MDs, and a Nikon F2 and F3, both with MDs. The tracks I went to, the only changes in exposure conditions that occurred were caused by the weather. I've attended a
lot of airshows too. Same difference.
After I got my F3, I'll wager I was like a lot of pros regarding its Aperture-priority Auto mode when they first got their F3s. I didn't trust it, preferring manual. Until one event where I decided I'd go ahead and leave the F3 on the A setting and see how it did. I'll admit, I was surprised by the results. All my slides were correctly exposed, but still, I attribute that to the 80/20 metering pattern it had and not the fact that it was calculating exposure from one instant to the next.
So anyway, you just can't make blanket statements like those above because there is ample evidence to contradict them. Like the thousands of slides in my archive, for starters.
EDIT: Oops, looks like I missed an entire intervening page of arguments. Oh well, just add mine to the majority.