If the hash of some data is computed and sent along w/ the data, can't an attacker alter the data, re-compute the hash and the receiver would be none the wiser?
In a data stream that is only hashed, then yes they can.
If you want to mitigate this you need to ensure that this cannot be done without detection, such as signing the hash and including the ...
TLS Channel binding is targetting to prevent MitM exposure of the both Secret (password) and Data.
SASL-SCRAM itself works in a way that it allows authentication without passing the password - password is used as shared secret to perform cryptographic operations on shared non-secret (nonce). That prevents MitM exposure of credentials however it does not ...
My understanding is that simply encrypting the data, even using a
symmetric shared key, with something like AES or 3DES should be
sufficient to verify the data has not been tampered with in transit.
If it had been, the message simply would not decrypt.
Your understanding is wrong.
Why would a message not decrypt if someone flipped a bit?
Even this ...