This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
You might consider contacting particular vendors (or finding their message boards) and asking them. I haven't seen much of a global trend, so its possible different companies have their reasoning. I suspect its properly because of laziness (and security)... they'd rather spend the time developing one good driver than 2 medium drivers, but thats a guess.