Save money and/or to get your own custom items authenticated. This is the problem the blue label addresses. That Mario Pikachu was for sale by the PSA employee that was fired over grading and selling his own weird fake cards/custom cut autos. Basically he’s the reason for all this happening.
I sent all mine that way for two reasons. I typically send in batches with other autos (pages, cuts, etc) and it saves quite a bit on each card + saves me from doing multiple orders which saves even more on shipping fees.
My current order has two pages, two artist proofs and two basketball cards, as an example
Couldn’t you just ship two orders in one shipment? I’m unsure if it works like that with the other items you mentioned, but it would at least keep the shipping costs down.
Overall it’s a pretty neat solution to the problem. I would’ve liked to see PSA not grade any copyright infringed cards (i.e. fake/custom cards), but I’m sure there are some gray areas that make this solution a lot easier for them.