Here in Florida I see the low side is insulated, but not the high side.(Residential)
Why is that?
I understand why the low side is.
If you understand why the low side IS insulated, you should be able to infer why the pressure side IS NOT insulated.
Roy, have you ever touched the high side line when in use?
That would give you a clue. 
Runs at a higher temp. Insulation is used to keep the low side lines from sweating, which is usually helpful in our hot attics. Less sweat, less damage drywall, insulation and trusses and better for A/C efficiency.
Marcel that must be a switch and bait question like what RR tried to pull up in the electrical thread:shock:
Fu ck You!