To add to Cimredopyh post, aquarium sides go straight up and often are higher than the bin sides. The angled sides of the bin allow more ventilation area.
I do see your point about bins scratching and bacteria, but bins are also very easy to wash well. An aquarium of that size is heavy and not easy to take to a tub or sink to thoroughly wash. Also, the area where the sealer is can hold bacteria.
Tanks also build up condensation easier than bins because there is less ventilation.
I thought there was only a concern about Bisphenol A if it contains food or water?