With the caveat that I am pulling this from very old memory, the deposit on cans is still more like 5 cents. If you collected them in bulk then you were paid by weight, which was discounted on the presumption of non-aluminum mass (fluid, dirt, etc), and some people would try to sandbag their cans. It wasn't a lot of money by any means but it wasn't nothing either.

There was a lot more can litter back then, so it was easier to collect. A side effect of aluminum recycling is that most of that litter was cleaned up by can collectors.