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There are many bets that have the opposite bet, there are bets that can overlap, when you check some sports book, there are so many markets, and sometimes it can be hard to find the right one... with good odds.
Yes progress have been made and great innovation too. Apart from that Op made an example of a particular player not scoring as a betting option like a goal or a number of goals, if it comes to team as a whole, I believe there is opposite option betting in terms of numbers of goals that the team will score. For example, if you are betting for under goals then you are invariably betting opposite that the team is not able to score higher goals too.
Yeah, a lot of betting options actually exists with their opposite betting option as well but like I did said in my last comment on this thread, it is not very much necessary that every bet option must come with the opposite; allowing bettors to bet either on one of the side, it's not very important because we already have a lot of market to choose to bet on to the extent that some times, its even hard to find the right one that gives some good level of conviction that we will win, and let's not forget that often times when options become too much, choosing one out of that many become really hard, especially when it's hard to find an option with a good probability of playing out and with a good odd.
Challenges like this can sometimes easily discourage a bettor from betting on a game he or she had intentions of betting on, they decide to wait for the next match, and a casino that really want to keep their users betting at all times will know better than get things complicated for their users.