Those cheap plastic bottles for drinks are never reused. They're barely recyclable.
Aluminum, on the other hand, is astoundingly recyclable. It is recyclable in the way a person thinks recycling would function: You can make like-new aluminum from recycled aluminum. We can recycle used aluminum cans right back into fresh aluminum stock to make cans again. It requires about 5% of the energy costs as new aluminum.
Plastic bottles are not this. If, and that's a big if, they get recycled, they get turned into other things for 1 more lifecycle. They become synthetic bits in clothing. They become parts of carpets. Then they become trash after that.
By contrast your aluminum can could've been through 100 lifetimes as a can previously and it'd be just as good. In the case of aluminum, it is only a waste of metal if people trash it.