I don't really subscribe to your logic, I'm afraid. For instance, I've had hardware drivers not work on windows 7, even though 7 is expressly supported, and indeed I've had drivers for hardware work on windows 10 even though support is specifically denied by the vendor. It really depends on what the specific lower level issue is, and only then can you talk about chance. Also, compatibility mode in the various operating systems goes a long way toward solving software running issues in my experience. I'm not making any claims specifically regarding plustek scanners mind, but I am curious as to whether the issues people are having with them are A) people avoid the products because of the absence of claimed support, or B) actual reported compatibility issues from people trying to use the scanners.
From what you've said, we seem to have had different experiences, so I imagine that's why we have different views. I found Win 7 pretty much worked fine, with the minimum of fuss and the occasional update (which admittedly I often didn't notice until I shut the computer down and was faced with a wait while it updated, which was annoying at times). My experience of Win 10 has been that it seems to be somewhat bug prone when it comes to recognising drives. My main PC, supplied new by a well regarded major manufacturer, with i7 processor, 16 gig of ram and SSD drive wouldn't consistently recognise the factory installed CD ROM drive, then lost the ability to read from it completely (similar to the SD card reader problem I have now), then it started working perfectly for no obvious reason about 9 months after taking delivery of the PC - perhaps one of those major update downloads fixed it?
If you do a Google search for Win 10 and SD card reader issue there seem to be plenty of people who've also experienced it, and only some have found a fix for it, so it appears it's not just a one-off on my machine. Furthermore, I've found Win 10 seems to be rather needy, with updates coming in on quite a regular basis, which take time to download and install. Fine if you use the computer every day and it gets on with it while you're working, but for an occasionally used laptop I find it's a PITA, with me having to remember to turn the laptop on and connect it to the internet and check for updates the day before I want to use it, as it can take a few hours to download and install the updates. Yes, I could turn the update facility off and update when I wanted, but I'd have something else to remember then, including where the turn off option is in the maze that is the 'Settings' menu. Perhaps if they didn't package it up with undeletable software like Cortina, Edge, ect. then it wouldn't need so many patches and updates to fix the bugs and vulnerabilities?
Back to the scanner, I use a flatbed v600, the downside is that you can get better results from something like a Plustek on 35mm, but the benefits are that you can load two strips of 6 negs in it and leave it to get on with scanning them while you do something else. It also seems to do an acceptably nice job of medium format. I did think about buying a Plustek for 'best' 35mm scans, but the desk space and expense couldn't be justified for the fairly marginal benefit I felt it would give me. So I get the lab to scan any films I think have got some good shots on, using my scanner on the 'everyday' type stuff, and I think that's a more cost effective option for me.