I think the confusion comes from the use, in English, of the word sort in phrases like "sorting laundry", "sorting recyclables", and "sorting mail", which is actually an "iterative filtering" (ie "grouping") operation. See http://en.wikipedia.org/wiki/Sorting and http://www.google.com/search?q=define:sorting

This is similar to the confusion between "and" and "or" I've seen people have when using computers to do searches. In plain English, "and" is often an expansion term, in that it often expands the result set rather than restricts it, similar to "or".

  go through that file cabinet and find 
  all records for Alice and Bob.

This actually means "give me records matching Alice or Bob", because the name/ownership/topic field is mutually exclusive (if a record is for Alice, it can't also be for Bob), and people intuitively understand that. So it expands to "give me (records matching Alice) and (records matching Bob)", not "give me records that match Bob from the set of records that match Alice".

Call me naive, but I didn't know there was any mystery surrounding filtering and sorting. I don't see any ambiguity there.

You're naive. Go run some user studies and observe how differing mental models affect how people interact with controls such as filters, facets and sorts.

A search engine that can sort by, say, date and give me results in real time would be pretty useful. Why not, Google?

A very helpful article for sites where filter/sort/search functionalities coexist.