#4 does... Namely legacy reasons.
I have a perfectly fine multipage scanner here that doesn't have drivers for Windows 7 and the manufacturer is out of business. You do know that Windows 7 implemented driver signing right? So even if you do find a legacy driver it probably won't start because it won't be signed. And don't give me this "Linux is your route" because no driver exists for it there either. So my choices are toss a perfectly working, expensive at the time and in demand scanner just to update from a working OS to one that doesn't or stick with what is working.... Hmmmm Hard choice that one.
It would have helped if you mentioned brand and model. Perhaps people could have helped you out...
Something is rotten in the state of Denmark. This bodes some strange eruption to our state. Contagious blastments are most imminent. Who is't that can inform me? (of how low England has sunk) And then it started like a guilty thing (soon Top Gear will be blocked) O villain, villain, smiling, damned villain! These tedious old fools!
I know what's rotten in Denmark: their cheeze smells like old feet
Software production is assumed to be a line function, but it is run like a staff function. -- Paul Licker