In MLB, why do we know most of the Umpire's names? I would have to say that part of the reason is just what I just highlighted. In addition, the umpire working behind home plate can be pretty well known to fans and players alike for what his strike zone is like. An umpire working the base paths could be put on camera frequently after making a bad call as well as the game wears on, such as his ruling on a hitter's checked swing, whether a batted ball was fair or foul, or when he misses a call about whether or not a fielder really caught the ball or trapped it if his catch was near the ground, and/or most of all, his call on a runner--was it really correct as far as him being safe or out is concerned? Also, an umpire who makes a bad call that decides the outcome of a playoff game, or even a playoff series, can be remembered for a long time.
in football, only the crew chief is ever actually on screen making a call and the other 6 refs are just in the background. and people certainly know crew chief's names. i don't watch the NFL enough to know them all, but i certainly recognize plenty. you also don't get a lot of player/ref interaction b/c players are usually getting back into huddles and thus separated from the refs after penalties. in baseball, really only the home plate umpire gets any significant airtime and since they rotate, there is only a 1 in 4 chance you're going to notice anyone from a crew. plus, they all wear masks and aren't easy to recognize unless an argument flares up. and even then, people certainly know umpires and their strike zones. also, interaction is pretty minimal. if you are called out, you get off the field, if you get a bad strike call, you get off the field or get thrown out. in basketball, there are only 3 refs, and unlike the other sports, they all are supposed to make calls and thus be in the spotlight. they aren't wearing masks, and like someone else said you can pretty much see all of them on camera the whole time. and maybe most importantly, there is tons of player/ref interaction because after a call, the refs and players are all standing on the court together which makes it very easy to talk to each other and get "and kobe goes over to talk to steve javie" or "marion is having a few words with ken mauer" type comments from the announcers which plants their names in our heads. in short, it would be weird if you didn't know nba refs' names much better than the other sports.
the refs in the nba affect the game more than those in baseball and football. and if you watch over a hundred games each year and those refs never retire, you're bound to remember some names and what they did.
It's not that we know their name. It's that we actually have to check who are going to officiate our games and be worried about some of the names showing up.