Of course RAID 5 and 6 are erasure coding. They use a code (e.g. XOR/parity) to tolerate the behavior of a binary erasure channel (BEC). Systematic codes (where some of the code stripes are just identity chunks of the data), like RAID 5 and 6, are probably the most common case of erasure codes.
Now, we could have an argument about whether RAID 1 is an erasure code, but that wouldn't teach us much.
Well, I stand corrected (and I don't have much knowledge to argue about this).
Re-reading, I see that in the storage world "simple" correction systems don't tend to be classified as erasure coding.
Were I say "simple", I think I'd say any correction system that's not parametrizable, as in "let's do a 17+3 in this ordinary dataset and 4+2 in this one that's very important"
About RAID 1, technically probably it is... although bit very efficient :D
Now, we could have an argument about whether RAID 1 is an erasure code, but that wouldn't teach us much.