I agree. There is quite a diversity. I found in New Zealand, most people only expected 20 hours a week realizing that you are there to see the country and that to work more than that, didn't allow you much time to do that.
I found in Europe that there were more places just looking for 'cheap' labour and would expect you to work the 'required' 36 hours a week (that's full time people!) while sleeping in non-heated rooms in winter and eating just vegtables.
A lot of my frustraion is actually with the website itself. I mean, really, 36 hours a week?! That's a full time job for work exchange!
When hosts would ask me how much I was willing to work, I told them it was dependent on what the exchange was. For instance, if a host could not offer accomodation (i.e., sleeping in my own tent) and the meals were really basic to where I would need to buy food to suppliment the diet, there is no way I'm working 36 hours a week. On the other hand, I had one host who put me in a very nice room, was considerate and gave me options for works and the meals were complete and diverse, I had no problems working the 25-30 hours a week that he asked.
I really wish the wwoofing website would make SUGGESTIONS for a fair work hour week rather than stating it as the 'norm'.
I also felt when writing the wwoof owner, that she had the 'customer is always right' attitude. Frustrating as in paying my yearly dues, aren't I a 'customer' as well?