I think there is a solution. If a buyer or seller addresses you with words that you are not comfortable with, just move on to the next buyer or seller and keep rinsing and repeating until you eventually find a buyer or seller who addresses you using the words you expect AND his or her deliverables also match your expectations.
In my particular case, I just concentrate on the deliverables, tat, pricing, instead of "dear, sir, madam".
If I was so touchy about "dear, sir, madam, etc", I would have lost lots of wonderful opportunities.
But, anyways, each one to their own, as far as individual expectations are concerned.