I know that's not true. I say this as someone who measures the power consumption of individual components, and even individual rails with a clamp meter. The OP measures an idle power of 67W. He has 6 x 8TB HDDs. These typically consume 5W idling (not spun down). So the OP's NAS without drives is probably around 37W.
A UNAS Pro without drives reportedly consumes 20W with no drives. Adding 4 x 8TB at 5W per drive, means your UNAS Pro config with drives probably idles at 40W (again, drives not spun down). That means you are 17W under his NAS idle power. So you claim your remaining hardware (Mac mini, 4 APs, 4 cameras) run in under 17W... Yeah that's not possible. 17W is peanuts; it's half the power of a phone's fast charger (~30W).
PS: for the OP, an easy way to further reduce power consumption is to replace your 500W PSU with a smaller one, like 250-300W which is still amply over-specced for your build. Because the typical efficiency curve of a PSU drops sharply at very low loads. For example at idle when your NAS pulls 67W from the wall it's very probable it supplies only ~50W to the internal components, so it's running at 10% load and it's only 50/67 = 75% efficient. The smallest load for which the 80 Plus Gold standard requires a minimum efficiency is 20%. If you downgrade to a 250W PSU you are enforcing a minimum 20% load for which the 80 Plus Gold standard requires minimum 87% efficiency. The load at the wall would thus drop to 50/.87 = 57W thereby saving you 10W.