This will make you some gold for about a day, then every lock on the server with nothing better to do will start competing with you. You would make more money camping certain NPCs and buying their rare spawn items to resell on the AH than you would doing this. It's been done, if it were a solid money maker all the gold leveling guides would have it in there - pre_BC there were many "taxi" services, for a variety of reasons. One guy on my server tried to set up an hourly "taxi" to Scarlet Monestary for Alliance without mounts. He lasted a couple of days.

Older players won't use you, because of the trick that's been around since the start of the game, where locks would summon people to the edge of cliffs or over the lava in Ironforge. It's funny, but it's been done a gazillion times, so people are going to be suspicious.