I think the point is that beyond total and complete global totalitarianism there isn't a great way for any government to truly tax the rich to the extent desired because there were always be another safe haven for it overseas.
I am sure some figure out ways, but you have to go in dodgier places.
This is a new development is the last 10-20 years, so there is progress. It should help people trust the system is getting fairer.
If one is against taxes, and uses lack of enforcement as a reason, I smell dishonesty.
The burden of proof is on you then. For you to be able to say that, you'd have to enumerate all possibilities and then provide evidence why each wouldn't work. In the meantime, it seems obvious things could be better without needing to be perfect.