DVD Rippers are Cheap and CD Transports are Not -- Why?

I have owned pricey CD transports from Wadia, Theta, and Levinson and inexpensive DVD RW drives built into music servers.  All are highly regarded for their ability to do the job -- the transports sound great and the severs rip bit perfect files without so much as a hiccup.  How do the ripping drives do their job so well at a fraction of the cost of the expensive transports?
I ask because transports are prone to break and parts availability becomes a problem.  My Wadia transport now is a very cool looking doorstop.  I am toying with the idea of buying an Oppo universal player but am worried it will end up a useless brick.
Any thoughts?