A prayer, strictly speaking, is a request. Some is in the context of divine worship; some is not. I can pray to you if I like — that would NOT be worship (latria) which belongs to God alone. Lawyers routinely send “prayers” to judges. I don’t know why you insist on blurring this important distinction.
I do not miss the distinction, but I detest the semantic dishonesty that attends to calling it “not prayer” when one speaks to St. Mary and even petitions her to pray on one’s behalf - an act that was enjoined neither by Christ nor the Biblical texts.