A bit more clarification, the page right now says:
"Sold by Spark Maestro and Fulfilled by Amazon."
While this is a 3rd party sale, it will be fulfilled from the inventory Amazon has from any other seller. It has to ship from the 3rd party to be safe from counterfeiting.
Not only is commingling inventory a seller choice, it is also not an available option for many products. Only certain pre-approved products are available for comingling. But the unfortunate thing is that as a buyer, you have no way of knowing which listing are from commingled inventory.
Does the buyer have any way to tell if an item is commingled, and if the seller they selected does not commingle? The pressure to get the buy box on competitive items means missing out on sales if you don't commingle.
It also only happens if they choose to do so. It's certainly the path of least resistance, but it's entirely possible for a seller to keep their inventory from being commingled while still using FBA.
"Sold by Spark Maestro and Fulfilled by Amazon."
While this is a 3rd party sale, it will be fulfilled from the inventory Amazon has from any other seller. It has to ship from the 3rd party to be safe from counterfeiting.