I understand the fact that a group insurance policy with a company over 50 employees does not require an HIV test, but smaller individual policies do. Exactly why is it like that? Is is always safe to say that you wont get HIV tested if you are applying for a group policy?

In a group policy, the risk is spread over the entire group and the premium is based on that entire group's experience and not the medical history of any one person. When you purchase an individual policy, the insurance company has the right to ask questions related to your medical history. If you have a pre-exisiting condition, this could affect your eligibility for coverage and the cost. I am unaware of any situation where an individual covered under a large group policy has had to submit to any medical tests prior to obtaining coverage.