My impression is that gas companies use a procedure like this out of an abundance of caution / because there are still very old gas appliances that could be around which could have this issue. But I don’t think it would be legal to sell them now, or has been for a long time.
EDIT: Apparently I am wrong about this, heaters require them but stoves (in the United States) do not. :-( This according to some undated forum posts, plus Wikipedia: https://en.wikipedia.org/wiki/Flame_supervision_device—“SD usage in consumer products differs among political units – in the U.S., FSDs are not required by law or regulation for gas range (or gas stove) top burners and consequently are not present on ranges in the U.S. [citation needed]”.
But I get the impression that modern gas stoves are always pilotless, in which case only the cooking flame would be an issue, which would hopefully always be supervised.
My impression is that gas companies use a procedure like this out of an abundance of caution / because there are still very old gas appliances that could be around which could have this issue. But I don’t think it would be legal to sell them now, or has been for a long time.
EDIT: Apparently I am wrong about this, heaters require them but stoves (in the United States) do not. :-( This according to some undated forum posts, plus Wikipedia: https://en.wikipedia.org/wiki/Flame_supervision_device—“SD usage in consumer products differs among political units – in the U.S., FSDs are not required by law or regulation for gas range (or gas stove) top burners and consequently are not present on ranges in the U.S. [citation needed]”.
But I get the impression that modern gas stoves are always pilotless, in which case only the cooking flame would be an issue, which would hopefully always be supervised.