This is the 21st Century, isn't It?

We rented a DVD yesterday that didn't have surround sound. It must've come from the discount bin, next to all the eight-track tapes.

This was a modern enough movie (Hart's War). It should've had Dolby 5.0, right? Someone tell me I'm not crazy! I assume that 99.99% of all movies from the past twenty years are filmed in surround. Is there any reason to convert them to 2 channel audio for the DVD?