Jim Peacock from Snooze Button Dreams asks, "Where did the phrase 'Going Dutch' come from? Is the source of "Dutch Treat" the same?"
The source is the same. It comes from a time when the Dutch and British were vying for colonial supremacy. It was actually a derogatory term used by the British as it really means that there was 'no treat'. There is a good explaniation at Word Detective . Scroll down a bit for for it.
Jim continues with the question "Why is it wrong for a coach or player to bet on his (or her) own team to win? Doesn't that just give them more incentive to win (which would be a good thing)?"
Generally speaking I would agree that betting on your own team to win is a good incentive, as long as it's only a one on one type of bet. But as we all know that there are many other ways to bet on professional sports. There are point spreads, over-under, god only knows what else. Plus when the bets are made to professional bookies it can take on a life of it's own if the gambler in question loses a large number of bets. Take the Reds for example. The bookie might have a large number of bets on the Reds to win a certain game. Pete calls up and is told that since he owes the bookie a large sum of money he can get some of it knocked down by losing the game. He hasn't bet against his team, but he sure as hell isn't going to manage the same way. The manager can control the game in so many ways to affect the outcome.
Another example would be to suppose that the Manager has a big bet riding on his team to win. He leaves his star pitcher in far longer than he normally would have in an attempt to win thus destroying the pitcher's shoulder and career. I think that there are enough questionable managerial calls without having to throw in the question of personal financial gain through betting. As a player I would want to know that my manager is thinking about the team first and not worrying that he legs are going to get broken if we lose.