Speedtest and ICMP is prioritized on all networks and gives and indication of the distribution network's best case ability only. To really gauge performance one has to view matters end-end and that requires a proxy somewhere upstream. Speedtest is not indicative of your actual performance, only of the potential performance.
Why doesn't someone (ISPA would never due to commercial interests) set up a proxy in data centres somewhere (say one in SA, the US and one in the EU) and do comparative testing on actual performance delivered over different ISP's networks with real use? Benchmark CDN nodes from various providers. Cheap VPS accounts would be able to fulfill that role.