I always show online on Amazon. Here in India, shipping is fee is the bill is over 500 rupees. However, when I buy multiple products at a single time, I do not receive them in a single package. They deliver the products in separate packages one by one. I am wondering if Amazon is at a loss for all this. I mean instead of shipping the products one by one at different times, they could arrange a checkpoint(probably the destination city) where all the products for an order could be collected and delivered in the same package. This would help them save time and money on delivery and packaging. I wonder if this is the case in countries such as the US. I am waiting to hear the stories from your side.
I cannot say what goes on Amazon because I have never received physical goods from Amazon. Most of the Amazon products are not shipped in my home country. However, I think I have answer to your question. There are various departments in Amazon that deals with different products. You buy an earphone and socks, these items will be delivered to you but they come from different departments inside Amazon.