Ever since they played cricket with both teams in white?
It's not necessary to have distinct colours. The batting side are holding bats, the fielding side aren't. The ODI/T20 colours are for show and selling merch - which is all good (oh, and that a white ball >>> white clothes could cause problems. Both teams could wear black or any non-white colour.).
Interesting, when they play the All-Star MLB Baseball game, every player wears his team uniform. As for cricket - there's no chance of confusdion between batters and fielders.