I've found two of each, the rare bugs are truly that, rare, but I really dont think cans and boots are that rare.
You might be running in parts of Towns that have already been picked over by other Gaians. 3nodding
I know that for myself, I will run into cans and boots every few screens. Not on EVERY screen, but on every few screens and that seems to be the 'norm' for me. Rare bugs, on the other hand (some of which I still have never encountered! gonk ), I have encountered on what seem to be blue moons - once in a VERY long while.