And IMO secure DNS is not a solution. Either this ISP behavior is made illegal, or it will remain an arms race (with ISP being clear winner for most regular users).
Just interesting that people who are smart enough to understand other fake things on the internet (that maybe some people not as smart as you are not understanding). But when it is some ISP tricking you, all of a sudden, everyone is up in arms about it.
It's interesting.
For that matter, I've never been able to find (and I've checked) that any particular site or connection type was actually given priority and more bandwidth. When the connection is slow, it's equally slow everywhere. When fast, equally fast everywhere.
Also I get the feeling that some people think the speedtest sites themselves are giving fake numbers. Why? What would they gain from that? And why have I never ran across this, despite using many speedtest sites on multiple ISPs?
However, the deal is mostly not about speed test sites but about ISP behavior. ISP may maintain a registry of known speed test sites and shape traffic so that you get great results on those.
Registries aside, your ISP may also be detecting and throttling BT and/or VPN traffic, shaping sustained traffic, etc., meaning you will tend to get good speed test scores but get slow speeds if you attempt to use your connection in a real-life scenario.
And back to speed tests, they do tend to prefer servers located very favourably for ISP but not for you, routing to server on same ISP's network in the same city by default (this may be overridable by a tech-savvy user). I would assume they have agreements with ISPs on hosting and maintaining those servers, making any sort of manipulation a no-brainer for the ISP.
All in all, I routinely get cases where a speed test reports great results but due to whatever reason I get really slow effective speeds.