OP, I think they’re taking the piss for being American and having an imperial tape instead of metric.

I’ve got the best f both worlds on mine. Metric on one side and imperial on the other. Canadian and having US materials is interesting sometimes.

From one to next they look really similar.

2:12 is low slope iirc. So 3:12 can use shingles, but not 2:12.

You’re right though, could just be a look choice on a higher slope. Could be a “trial” roof or something who knows.

Canadian, eh?

On metal roofs they actually add grips so the snow can’t slide right off.

A sheet of snow isn’t light, you DO NOT want that sliding off and hitting you, but it’ll also fuck your eavestrough up.

Low slope, so considered flat for most codes, can’t use shingles. Basically every commercial roof has rocks, but In the last decade they’ve shifted to a vinyl. Lighter, handles more snow load.