The real problem is that in UK they don't want to understand that all GFSI standards are equivalent
I think the real problem may be that the UK doesn't view the value of the GFSI-benchmarked schemes in quite the same way, and even for BRC AA+ sites physically in the UK, it's still commonplace for multiple retailer announced and unannounced audits each year. In part this is because they are to some extent locked in a cycle of making "competing" standards of their own - pretty much the exact opposite of what BRC was originally supposed to do 
These days we assume that GFSI is treated more as an "entry level" requirement for a lot of our UK customers - without it they probably won't even bother considering you (and many of ours have e.g. contractual clauses that delist us instantly if we drop below a grade B at BRC), and with it you're considered good enough to qualify to start the actual assessment process.
Having said all that, IME there are parts of the UK industry that do have issues with wilfully ignoring the principle of the GFSI benchmarking process and blindly assuming that BRC is "better" (or not bothering to think about it at all, and just taking it as the easiest approach to a box-ticking exercise that doesn't actually help anyone). And it's not just BRC either - I've had issues with clients insisting that results from labs with ISO17025 accreditation are not acceptable, because they will only accept results from labs that are accredited with UKAS.
Of course the other element is that we want all of these extra things but don't actually want to pay for them, and I've had various suppliers over the years say that they simply don't want to offer product for the UK market as it's not worth their time.
I can't imagine why we're not the most popular country in Europe 