People need to remember that CSCS is not just about passing the H&S test. It should be about confirming that individuals have appropriate skills, knowledge and experience (never mind that competence also has other parameters such a physical capability etc). My qualification had to be compared by NARIC. In addition, if I recall (back in 2005) they also checked experience and I had to get a manager from my company to sign off that I had what I said I had. So by sending in copies of the CV's / job descriptions and foreign qualifications compared by NARIC, this would go some way to checking knowledge and experience (not exhaustive, but perhaps better than no check at all). In this regard, I am not sure they are discriminating. My advice, give them what they are asking for to get the cards. Whether you think CSCS is worthwhile is irrelevant - if its going to stop you working on a site, then it's always going to be a blocker.