Very few scanners will use sprocket transport for 35mm, really just minilabs doing scanning before it's sliced I'd think. Also much of the film community leans towards medium format/large format (if you're going to the hassle of dealing with film, make it worth it in quality, basically) which don't have sprocket holes at all.
Virtually all film scanners past and present use a film holder to make the film easier for the scanner (and the human) to manipulate and to offload the problem of film flatness to a sub-assembly. That's completely normal imo.
You are correct though that the film scanner market is dead as a doornail, film isn't exactly a high-volume business (however, afaik it is slowly growing however - that market hit bottom in the early '10s and Kodak/Ilford sales are growing these days). The entire market consists of the Epson V600 at the low end, Epson V850 Pro at the high end, and then Hasselblad makes the Flextight line at the professional end ($12-15k). Then you've got various old/discontinued models with varying level of support. So VueScan is really doing a solid here keeping that hardware in service.
One of these days I need to upgrade my V500 (predecessor to the v600) to a V850 so I can do large format on a flatbed. Right now I am using a Polaroid SprintScan 45 Ultra (which is a SCSI scanner that is only supported on VueScan anymore). I would love a Flextight but it's not justifiable and the options for a modern CCD (which, in parlance, is basically the opposite of a flatbed) are nonexistent other than that.
Unfortunately doing anything other than 35mm brings a massive jump in price, so I think it's here to stay for a long time. I loved doing medium format/120, but it's absolutely cost prohibitive. Minilabs scanning before it's sliced? Oh hey that's me!
Basically film development has become so expensive that it's more economical for me to either develop (or have developed) the roll and then scan all the pictures to see what they are. Realistically, I have nobody to share prints with, so any photo I want to share has to be digitised anyways. The TIFFs /are/ the prints now.
Film holders make my life pain since alignment becomes a huge problem, however film carriers are good. They're usually some roller assembly that may or may not have a thru-path (in the case of my nikon it can take up to 6 frames before bottoming out). Sprockets are usually counted optically - I've never actually seen something that physically engaged with the sprockets. I've tried using a flatbed but the time spent aligning (during which dust has an opportunity to come to the party) and slowness of the scan means what used to be "1 hour photo" is now more like 3 hours. I explored pacific rim's primefilm options, but swore them off when I discovered 2 scans of the same image would have odd distortions. The stepper motor was vibrating the CCD!
I know a lot of people use Epson flatbeds at the low end for a hobby, but how can you deal with that massive time sink? I've been on the edge about trying to create one of those camera based scanners. I've seen plenty of small trapezoidal scanners that are definitely a smartphone camera pointed at a light box, and I'd actually be fine with this, but they almost always just output pre-baked jpegs to an sdcard for grandma. I've been toying with the idea of recreating one with a raspberry pi & their "pro" camera so that I can have controls over the scanning process. Literally any control at all would be nice.
I still miss my old sony scanner's ability to set a film colour correction profile by reading the barcode on the edge of the negative /and/ set the frame count and filename in a batch from that data.
Virtually all film scanners past and present use a film holder to make the film easier for the scanner (and the human) to manipulate and to offload the problem of film flatness to a sub-assembly. That's completely normal imo.
You are correct though that the film scanner market is dead as a doornail, film isn't exactly a high-volume business (however, afaik it is slowly growing however - that market hit bottom in the early '10s and Kodak/Ilford sales are growing these days). The entire market consists of the Epson V600 at the low end, Epson V850 Pro at the high end, and then Hasselblad makes the Flextight line at the professional end ($12-15k). Then you've got various old/discontinued models with varying level of support. So VueScan is really doing a solid here keeping that hardware in service.
One of these days I need to upgrade my V500 (predecessor to the v600) to a V850 so I can do large format on a flatbed. Right now I am using a Polaroid SprintScan 45 Ultra (which is a SCSI scanner that is only supported on VueScan anymore). I would love a Flextight but it's not justifiable and the options for a modern CCD (which, in parlance, is basically the opposite of a flatbed) are nonexistent other than that.