Because they don't know any better because they have not bothered to investigate the rules. Upon inspection by ATFE (and by excepting that FFL you agree to a formal inspection by ATFE inspectors once a year, and at their convenience), their minds might get changed for them! In the spring of 2020 I will have had a FFL in the same location for 21yrs. In these past years I have seen many others loose their FFL (and livelihood) because they have not bothered to investigate the rules that must be followed if you are going to have that FFL. Simple rules at that! redleg1013 had no trouble providing a portion of the rules, but there seems to be many that don't even open the 'book'. If ya' can't find it "in the book" or on the ATFE web site, a call to your local ATFE office may get you an answer to your question or it may get you information as to where you can get the answer to your question.