My mother who is a senior citizen will not touch eBooks. She has a computer, iPad and iPhone but will not have anything to do with eBooks. I've told her she can adjust the font size for easy reading and that she can read right on her iPad which she uses for other things but no. She will only read books printed on paper.
Granted, that's a sampling of one but, as Hopscotch demonstrates, I'm sure she's not the only one.
I tend to prefer printed books too. I don't need to charge anything to read them, for one thing. They're also not subject to being altered or removed outside of my control. And, odds are pretty low that someone will break into your car to steal a paperback book left on your seat.
Also, it seems traditional publishers seem to price their eBooks at or about the same price as a paperback. So, if a paperback is $9.99 and the eBook is $9.99, I am probably going to get the paperback. Now, if the paperback is $9.99 and the eBook is $3.99, I would probably go with the eBook. Now, if you can buy the paperback and get the eBook for free, obviously I'm likely getting both.
With indies, since we have to use POD for paperbacks, our paperbacks tend to be priced quite a bit higher than eBooks. So, if you sell far more eBooks than paperbacks, it may be a pricing issue more so than a preference issue. I prefer paperbacks but when you need to maintain a budget, you have to go with what's less expensive, especially if there is a big difference in price as is typically the case when looking at indie works.