It's actually a lot closer than people think. BJS is not a huge name in the UK. He barely fought in Wembley, usually fighting in smaller arenas on smaller cards. His popularity is much, much closer to Liam Smith than it is Amir Khan.
Here's a google trends comparison of the 3 Brits:
https://trends.google.com/trends/explore?date=2016-09-03%202018-06-03&q=%2Fm%2F03qlzg4,%2Fm%2F04qfsh,%2Fm%2F0ywwwkj
trends.embed.renderExploreWidget("TIMESERIES", {"comparisonItem":,"category":0,"property":""}, {"exploreQuery":"date=2016-09-03%202018-06-03&q=%2Fm%2F03qlzg4,%2Fm%2F04qfsh,%2Fm%2F0ywwwkj","guestPath":"https://trends.google.com:443/trends/embed/"});
In comparison, here's what happens when you add Golovkin and Canelo on top of them:
https://trends.google.com/trends/explore?date=2016-09-03%202018-06-03&q=%2Fm%2F03qlzg4,%2Fm%2F04qfsh,%2Fm%2F0ywwwkj,%2Fm%2F07rsdm,%2Fm%2F065z6wp
The point is that Canelo-BJS in Vegas sells the same 250-300k PPVs that he sold against Liam Smith. On the other hand, Golovkin has previous exposure to the UK audience vs. Brook. That was his introduction to the UK. Since then, he was part of a huge PPV event. He's more popular now. If they put Golovkin in Wembley, that sh1t will sell out in less than a week.
Actually this trends graph is better at making the point. In Aug-Sep of 2016, we had Canelo-Smith and Brook-Golovkin. Their internet popularity was nearly identical.
trends.embed.renderExploreWidget("TIMESERIES", {"comparisonItem":,"category":0,"property":""}, {"exploreQuery":"date=2016-08-03%202018-06-03&q=%2Fm%2F03qlzg4,%2Fm%2F04qfsh,%2Fm%2F0ywwwkj,%2Fm%2F07rsdm,%2Fm%2F065z6wp","guestPath":"https://trends.google.com:443/trends/embed/"});
Yea, those charts don't show anything except how desperate Canelo haters and g fanboys are to disprove the truth.
The meaningful numbers is ppv buys. Canelo gets over 700k for Khan, and gets an automatic 300k regardless of his opponent. g has had one ppv fight that didn't involve Canelo and got a solid 97k.
Canelo got 300k for freaking Liam Smith. Which your chart and post say that interest in g-Brook was close to the same. The fact remains, Canelo is a ppv fighter and g is not. If g would fight professional boxers most fights, he could be a ppv fighter. But he never has and never will, g lacks the cahones to dare to be great. And that is why everyone would make more against Canelo.
It is not half as close as you imagine. Liam Smith gets 300k and Khan gets 700k against Canelo. And regardless of any retarded charts, the fact remains those are hundreds of thousands of people paying to watch Canelo. That g can generate almost as much interest when his fights are free, only shows the huge disparity between the two. Against g, the fight is on regular hbo. Against Canelo and it is on ppv and guaranteed to do at least 300k.