The laws regarding the use of a traditional straight razor vary depending where you are. I believe for barbering here in Ontario the replaceable blade razors need the blade changed after every use. Barbicide is not considered effective against blood pathogens here. I believe that happened the same time AIDS became a major issue.A couple of points Bob. Firstly I’ve never seen a Feather type razor in any hair cutting shop - they tend to use the cheaper shavettes that take DE type blades. Regarding legislation - over here I’m not sure that legislation bans straight razors or requires a new blade after every use - certainly my old barber kept a shavette in barbicide for cleaning up the nape. I assume she ditched it at the end of the day. I imagine the ones offering a full shave change the blade after use.
I go to barber shops to have my hair cut and also not seen a Feather Artist Club shavette used to do a hair cut but only facial shaving. My guess is that Hair dressers as opposed to barbers will use the less expensive replaceable blade razors rather than the Feather shavettes as they do the job and saves money. They are business people after all.
Bob