If it cost you $5000 to install you paid way too much.
Not sure about USA but it should be close, the Canadian code states that up to 15A you usually don't have to provide a primary fusing, being that the smallest size commercially available breaker is 15A and the lowest gauge acceptable for wiring is 14 and that the objective of the code is o protect the wiring.
The system costs $1700, and local installers usually inflate that by 3x.
I know a guy who does it cheaper, and is very experienced, but at the time my AC failed, he was not in the town, and 90F was killing me in mid summer.
So I asked the company with the shortest queue, which probably is not the best idea.
The AC has a rated power of 8kW for the indoor unit, mostly dictated by the heating strip.
Sure, a failed xfmr won't burn the thick wires, but the xfmr can burn the air handler, then my house.