The building company is always responsible for the dope, and should make sure he is working safely. If the dope does not have enough smarts for the job then the builder should take them off it or have it done only under supervision of someone who does have enough smarts.
I use my boy on sites sometimes and he is genuinely of help, but I have to be careful about how and what I ask him to do. I would not let him near a chop saw.
E.g. he can read fine, but some guys on site can not read or don't have a good grasp of english, so "do it as the instructions are on the packet" is not going to cut it. ( this is nothing to do with immigration or foreign labour, but the same can apply)