This title’s a bit confusing, so let me explain this better.
A customer places a bunch of separate orders with a shop at different times. (Some may be preorders, some may be in-hand items.)
Each time an order is placed, shipping is charged for each order. So every order will be shipped separately.
The seller waits for all the items to arrive. Then ships all the items together in one package. They don’t refund the difference to the customer, but they pocket it.
So I’m asking:
1. is that illegal? It’s definitely unethical; it sounds like mail fraud to me. But I’m not sure if it is or not.
2. is this against any Shopify terms of service?
This is normal and legal, just made the clients unconfortable. In mostly cases, clients shop multiple products value exceed 100 usd will apply free shipping strategy instead of charge seperately, however, different sellers have different strategy, they may have low profits or different situation. If you met this issue, you can ask the customer service to ask them return you the difference.