Business attire is quite often expected of professional athletes in North American pro sports.
Watch an NHL playoff game pre-game show and you’ll often see shots of the players arriving at the stadium; they’re usually wearing suits.
In basketball and football, a complete set of players from both teams are on the field when the game ends. So there’s plenty of casual contact when leaving the field of play.
In baseball, one team has its full complement on the field, and the other team has no more than four, but most often only one of its players on the field when the game ends.
NHL players are apparently required to do so. The NBA caused a bit of a stir a few years ago when they instituted a mandatory dress code.
It’s also not just pro sports. I only ever played high school sports, but we were required to wear a shirt and tie on game days for football.
Except in the case of a walk-off home run in which case pretty much the whole team is out there. 