In America you have most of the rights of a citizen at age 18, but there is a massive class disparity and pressure to strive for upward mobility. Some gatekeeping is done systematically by university credentials (half of adults have attended university while one third have a bachelor's degree).

Within the university itself, there are groups that have well-developed economic connections, the same organizations that perpetuate class sortition. This sort of thing happens organically anywhere that it is permitted. Wealthy people find each other and make organizations that allow them to socialize with other wealthy people, and take advantage of poorer people. A key ingredient is alcohol: in the US, the age to buy and possess alcohol is 21, so students under that age need a connection to get it. With property, access to alcohol, and social connections, fraternities can easily pull off parties that are appealing to young adults who are looking to be superficially transgressive, to fit in, and to meet people.

An American frat becomes this coveted in-group identity that people are selected for by either wealth or subservience, which is where hazing comes in. The fraternities and sororities also have a lot of power over the norms of masculinity and femininity.

In my experience, frat parties are extremely boring, usually with overplayed music playing way too loud, alcohol and unknown other fluids spilled all over the floor, and dozens upon dozens of people that are very conventional and devoid of personality.