That should not occour - I suspect it is because the insurers can effectively claim the VAT back, therefore they are merely watching their own pockets than actually applying appropriate standards.I'm currently struggling to get insurers to accept a properly qualified electrician working on commercial premises just because the electrician is not VAT registered.
I had the same happen with a carpet claim some years back. My prefered carpet fitter stated "Insurers always refuse my estimates because I am not VAT registered" therefore refused to estimate. Although when the claim went thru their carpet firm they often used then the actual fitter himself was not VAT registered.
I also noted (said by all involved - including the insurance co loss dept themselves) - We expect as standard practice to be given a 10% discount because we are an insurance company.
Looks to me that their headline view is 10% discount and VAT registered (we all know that the notational 10% discount might actually be Rollox in practice)