Depending on the setup it can be eco tourism. Especially if you pay them a little. It's legal to do a course on local farming techniques while on vacation, for example.
In practice you probably wouldn't be useful to them as a worker so fair enough.
Anyway, don't ask these questions here, ask immigration of the area you plan to stay at.
I've received people's private info, passport copies and bank statements, from immigration in Thailand. They reused old papers. When I mentioned it they proudly replied "yes, we recycle!"
