My apologies Chronus, I messed up the quote function on that one....
You are quite right about the requirement for rigorous, thorough and relevant training coupled with frequent use and recurrent training. Yes the FAA only requires one written 20 question exam for the IR versus a minimum of 7 exams for a PPL IR in the UK...but the training is about the same and in fact whereas a UK IR holder can do a revalidation flight and then not fly at all, let alone conduct approaches to minimums, for 364 days and still be legal to fly, an FAA IR holder must have conducted 6 approaches in actual or simulated IMC in the preceding 6 calendar months to remain current....this can be difficult for a pilot not flying for a living and as a result many if not most will undertake an IPC roughly every 6 months. So the main difference is the huge effort required to pass the exams. Only two exams can be taken in a given sitting and they can only be held at a limited number of inconvenient locations. Their value (vs the FAA approach) is questionable and they are a legacy from the fact that the UK training industry is set up for basic VFR PPLs or airline pilots...PPL IRs are not really catered for. So that is one of the drivers for private individuals with a life who can't take six months to live in a residential training facility like aspiring airline pilots.
But as I mentioned in my previous post, EASA has made it a requirement that regardless of aircraft registration, if you are a resident of one of the EASA states then you must have an EASA licence. Most (all?) EASA states elected to claim the available derogation t extend the deadline for this implementation and the latest extension has taken it to April next year, although it may be extended further.
Also although the more readily obtained FAA IR may no longer be a driver for business people flying an N-reg aircraft, there are many benefits to operating an N-reg aircraft over a G or F or D with regards to the available STCs for various mods, the direct owner control over maintenance which contrary to popular European myth, follows the same manufacturer recommended schedules and although for example, the UK allows engines to run on-condition past their TBO, many other EASA states do not.
Hope that explains it!