Really? That is amazing. Just a Part 91 "liberty"? Even if not required, I think it would be rather imprudent not to have an OAT when flying IMC.
OAT is required in Canada both for night VFR & IFR, and I expect most elsewhere by ICAO.
IIRC, Canada also requires a special rating to fly at night. In the US, night flight is a basic private pilot skill, and if you aren't able to meet the standard you get a special restriction on your certificate prohibiting flight at night.