I am pretty sure he mentioned putting a lift in.I think 8” concrete is totally unnecessary for your use. Also, most 6” concrete is actually 5 1/2”, 8” is 7 1/2”, etc. I believe this comes from the days of using wood forms....2”x6”, actually being 5 1/2”. I had 2’ of dirt and clay dug out under my slab and had 3’ of engineered fill(basically sand) hauled in and packed for the base. They lined the perimeter of my building with 4’x8’ sheets of 2” dense foam board for a frost barrier, then put rebar on a 2’ grid throughout the entire building before pouring it.
4-6” concrete without rebar reinforcement isn’t thick enough for a decent lift with a 8-10k on truck hanging off of it.
Just went through this with a huge ordeal at work and lifts. Plus personal experience with it.
@buildingup can chime in.