It may be that the term “loophole” is what threw me off here. Loophole is something that relates to tax evasion, which is not legal to begin with. It's not something that you make people comply with. It's something that you enforce and stop, so that's what I was referring to: enforcing against illegal activities such as opening accounts in foreign countries and not reporting the income. This is something that I had not heard about, enforcing against those types of planning.
I am not talking about specific measures to curtail tax minimization strategies, which may appear unfair. I must admit that the government has done some work on that in the last few years.