I'd bet that less than 5% of the public knows that GC and MF are one in the same.
Why not just use the same name for both?
This one is really easy to answer. Sales tax. If there is a brick and mortar GC in your state (and your state has a sales tax) they collect the sales tax at time of purchase. For MF, you pay your sales tax when you do your taxes. MF doesn't collect it.
You do pay the sales tax from online purchases on your income tax form, don't you?
Eric