The thing with these types of people (realtors, restaurant mangers, etc.) is that you can make something extremely easy to use but there will always be effort in producing new content; effort they are not willing to expend. Time and time again I've worked with people who couldn't be bothered to enter the data for their new listing or upload photos. They always feel like it is busy work and better farmed out to an assistant or done by myself at a unsustainable cost. Maybe the problem is that most of these people are technically inept and/or can't type more than 10wpm, I don't know. I've completely given up on anything real estate related and refuse to take any projects in that space because the failure to produce new content and maintain a web property always gets reflected back on me, as if I made something too hard for them to do. Plenty of dead-simple options exist to create and maintain a site, I find the issue is lack of cooperation with the site's owner to produce new content.
Now in the food service space, you could easily auto-generate an update based on the POS inventory. The problem there is many restaurants use a system like Micros, which has data access, but refuses to open it up to third-party vendors. If Micros ever wised up and opened an app store where customers could install approved and signed apps, the person who bridges inventory to web will cash in and retire early.