So… they charge half the price Apple does, and if you don't want to pay it you don't have to care because it's a standard m.2 so you can swap it with a retail drive (at which point you have both the original and the replacement for 50% more storage at a lower price), which you can't do with a soldered Apple drive.
Looks like the test is done by just copying a large file and measuring the time it took. This, of course, gives some idea of performance, but they are quite many things that can affect the results.
On the original article[1] the table also shows results from a synthetic benchmark. This shows 2.6GB/s for Macbook and 1.2GB/s for Dell XPS. They also mention that it's a bit apple vs oranges, since different tools were used for the benchmark.
It's the difference between cheap SATA SSDs and expensive NVMe PCIe SSDs.
Search for comps on any online retailer and you'll see how expensive and fast those are.