I agree that that OSHA is there for employees..Yet Safety programs are the employers responsibility..so being self employed does not relieve you of your responsibility of being safe..
So you are a one man shop working on a job site and one of the other contractors employees are injured in a accident..OSHA looks at the whole site and all the contractors..the GC is held responsible for everyones safety and if you are employed by the GC it is his responsibility to make sure you are in compliance..so even though OSHA can not fine you as a one man shop you are still responsible to be safe..