Sports betting are widely used throughout the world.
No. Rather sports betting is a niche gambling,, popular in some specific groups and spedific "cults" which promote such gambling along with local prevalence of such games which have an association with sports betting. For example : rugby, mixed martial arts, tennis and soccer.
Most of the gamblers bet on different games even in streets and the bet price is very small because most of the betters are not professionals.
Bet prices can vary. It is not fixed to be "small".
Two people bet on a match and one wins at the end and thats all. This thing has increased the level of sports betting which is not good for new generations.
Thats a casual bet not something that bookies run. While casual betting is not harmful playing a sportsbook in often addicting.