Yeah, but let's see if they get the apple example before we throw all that at them.

I fully forgot about thousandths even though I see them all the time as "mils". Definitely metric but worse.

We do, but centimeters are in a weird spot. In general they are just a bit too small to be used in place of inches and too big to be used when you need millimeters. Also, inches easily go into feet which then go into yards. Probably the closest function to that would either be decimeters or fractions/decimals of a meter but that doesn't really feel great either. There's also something to be said about functional accuracy; for measurements that don't have to be exact imperial units feel pretty good. For example, I might say that a cardboard box is about 1cubic foot if it looks about 1 ft in length on each side. If I instead used meters, 1 ft is about 30 cm (30.48 cm) or 0.3 m which would translate to 27,000 cubic cm or 0.027 cubic m. You might round that 0.027 to 0.025 or 0.03 cubic m depending on if it's more or less than but it's still feels like a weird unit for our rough approximation.

Another quick example, my foot size is approximately a foot in length and I paced off a room at 10ft x 20ft so the area is about 200 sq ft. The equivalent would be that my foot is approximately 0.3 m so 10 steps x 0.3 m x 20 steps x 0.3 m = 18 sq m.

Imperial units work well when you want to use relatively small whole numbers and high accuracy isn't super necessary, but ultimately it just comes down to preference.