Why do nba teams wear the same colored sneakers sometimes?

I know that some nba teams have a tradition of wearing certain colored sneakers during games (the bulls used to always wear black sneakers on the road). Also, it seems like alot of guys on the Lakers wear purple sneakers. My question is why do they do this? Is it to promote team unity or something?|||its very much to promote team unity it shows they are all a team and you cant deny while watching the world cup this year anyone not whering the same cleats did stand out and its looks sick to see the magic come running out wearing those sick blue nikes i forget the name but they are awesome kicks|||The Lakers wear purple sneakers because a major part of their team colors is PURPLEE|||Because who wants to wear an orange sneaker if your team colors are black and purple? just saying.|||TEAM COLOORS