It's trauma and/or fear that fuels it. I get that it is deceptive for the other person who is being lied to, but people do things out of survival and/or aren't properly taught that truth is safe. People lie for many reasons, many that are not personal to the other person.
Nothing worse then bad actors who go out of their way to ruin other peoples lives.
There are still some very good people and communities out there though, its just a matter of crossing paths with them