Why hasn't Charlo fought Tszyu yet? Why is he ducking Tim?

So what you're saying is Tszyu fought the best but Charlo didn't? Did little twin not take every belt by force? He literally won every belt he has by knockout victory over the other reigning champions. Then (albeit foolishly) tried to make history hopping two division (with MW to SMW likely being the farthest leap between weight classes) to take on the king of that division and number one draw in the sport?

You can call little twin a lot of things but not a ducker. He doesn't have enough clout to duck anyone.