Reality shows are fake

Reality shows are usually not scripted, just very produced behind the scenes. Usually the producers will set up a situation or storyline and just let everyone ad-lib the lines (sometimes with retakes). This format became very popular in the late 2000s because studios don't have to hire script writers.

The reason why it seems so fake is because of the producers trying to form storylines in sometimes a not so organic way. Either by editing the shots or heavily controlling what the people in the show interact with.

There are also people who realize that being crazy will get them more screentime, which leads to people playing up a part. This is very obvious in later seasons of RuPaul's Drag Race, they intentionally will keep queens around if they "make good TV". You can often tell who is going to win too because they are given more screentime and praise.

In a lot of the "helping" reality shows, they are super vetted before hand. Producers will often scout out locations long before the host even shows up. And in cases like Catfish, have all the information on everyone before starting to film. I heard that it's often the Catfisher who reaches out of the show, not the other way around. In home buying shows, the couple will often already have bought a new home, and ultimately be the one they pick in the end. They have to pretend that they are shopping for a new house even tho they aren't.

Once you get to reality game shows the monetary prizes involved tend to make producers much more scared of getting sued if something is faked. So, for example, Survivor is 100% real because if it wasn't they'd be sued out of existence.

There are also reality shows that are like 90% real with some fake parts. "Next time on Hell's Kitchen" is a phrase that will haunt me in my dreams.