AFAIK Falcon 9 is using automated friction stir welding, which was only invented in 1991 and first used on rockets in 1999 by ULA. So there is definitely consid

AFAIK Falcon 9 is using automated friction stir welding, which was only invented in 1991 and first used on rockets in 1999 by ULA. So there is definitely considerable progress in welding that has been done since Apollo. As for Starship, IIRC friction stir welding of stainless steel has not really been done, definitely not at scale so SpaceX will have to use more "traditional" welding methods, which have still got a lot of improvements and new techniques as well since the Saturn 5 times, as mentioned in other comments.