I know... but it's not rocket science. I will test everything with US labs, on every single batch. I will also make sure the supplier understands I will test everything. The assurance on Alibaba means I can "chargeback" if I prove they provided a fraudulent product.
I suspect it's white label suppliers that recognize when they are working with a non-sophisticated brand (I'm a materials engineer), and the brands are unknowingly passing along adulterated products.
It is not about absolute cost, but cost of my time to get a small initial batch of say 1000 bottles to get going.
Even from Europe I would want to do a US lab test since it really doesn't cost much to analyze.