If the answer is none, which I think is highly likely, you need to wind your neck in as obviously do not know what you are talking about making comments such as that.
No offence taken, but I do know exactly what I'm talking about and strive every day to solve these problems. There are five main reasons for the lack of proficiency.
1. The previous ICAO test did not test operational language and Slade created a washback effect wherein focus was on the test not on genuine language proficiency outside of the limit of the test. This incidentally had not changed in five years.
2. ICAO level 4 as a global standard is not exactly great. It is illegal for an airline to insist on a higher standard.
3. Culture
4. Attitude of language professionals that think they know everything.
5. Attitude of aviation professionals that think they know everything.
When you have first and second officers that can't distinguish "there are fumes in the cabin" from "there are films in the cabin", or can't distinguish common words you have a problem.
Interviews are sometimes a good tool for assessing language proficiency, and I do partially agree with you there, but there are some things that a need a language test with some scientific data behind it.
Also language proficiency can deteriorate - there are many reasons why. If your experience within CX has been different then good for you. I hope it stays that way, but please consider that there are language professionals that are trying to improve communications and changing the attitude of people that don't know what they don't know is our biggest battle.