The speedtest location, VPN provider and the VPN server are all chosen randomly for fair results. All speedtests are performed using OpenVPN over UDP (with the providers default settings) from Vultr VPS servers geographically close to the VPN servers.
To find the maximum speed of a each VPN server we need to test from a location geographically near the VPN server. For example if you wanted to find the maximum speed of a VPN server in Amsterdam, then you would need to test from Amsterdam. This limits any network bottlenecks between the test server and the VPN server. The test servers have gigabit network connections with good peering to Internet exchange points - which is faster than any home internet connection.