Yeah Crossroads wasn't as much a place for PvP as much as it was a place for Alliance players to dick around with NPC's and lowbie Hordes who were PvP flagged.

But Tarren Mill is pretty simple, and Stranglethorn Vale even moreso: it was an important zone for each faction's leveling and it was the first expanse of contested territory that saw a lot of traffic from both factions, thus fights broke out and people would just spend all their time fighting.