Let's say you're a CISO and it's your task to evaluate Cybersecurity solutions to purchase and implement.
You go out there and found out that there are multiple organizations that tests (simulate attacks) the EDR capabilities of these Vendors periodically and published grades of these Vendors.
You found the top 5 to narrow down your selections and you pitted them in PoC which consists of attack simulations and end-to-end solutions (that's the Response part of EDR).
The winner gets the contract.
Unless there are tie-breakers...
PS: I heard others (and read) said that CS was best-in-class which suggested that they probably won PoC and received high grades from those independent Organizations.