As in the words tin - can, taxi - cab, autumn - fall, lift - elevator, etc. Would these be considered as absolute synonyms?
Well, those are among the first candidates to be called absolute synonyms if we do accept the existence of absolute synonyms, but there are always arguments for the opposite idea. For example, autumn looks a bit different in different places, and that referents of autumn and fall may differ between speakers. Both taxi and cab are cars carrying people for money, but what you see, imagining cab is not the same to what you see, imagining taxi.
Every lexeme is a social marker and every speaker's choice is a certain marker. Choosing between more simple and more scientific name, more common for the speaker and more common for the interlocutor. Wilson's question makes a lot of sense:
What is an "absolute synonym"?
If the answer to that is "when there is no context in which changing the word to its synonym would change the sense of the phrase in general", then yes, autumn and fall are absolute synonyms.
However, if the answer to that is "when changing the word never affects interlocutors perception", then no, they're not absolute synonyms. And, furthermore, notwo are.