Both buyers and sellers need each other to survive and as buyers, we need to treat all sellers nicely but also be careful so they don´t take advantage of such on you. What the woman did was unfair, it´s obvious. She could have just dropped it and left instead of throwing such away. At least, she will also be a seller in her own place too.
this is what some buyers tend to forget, for an economy to grow both the buyer and seller plays a vital role.
I believe she also sells a thing or to but today she's a buyer, she turned out to be an arrogant one.