I think that most people have one of two basic reactions whenever they come across a spider (or any other arthropod/bug) in their home. There is…
1) “ACKK that thing is sooo gross ewww UGH smush it/get it out of here/flush it down the toilet!!!”
or there is…
2) “Aww poor lil’ guy, why are you inside? Let’s put you back outside where you belong!”
While the tone is a bit different in each of these reactions, the message is the same: many humans believe that bugs don’t belong inside the home. Yet, we find them in our homes all the time, and we spend a lot of time/money trying to eradicate them. So, then, is it true that spiders don’t belong “inside,” and if not, why do we feel this way?
The answer to the first part of the posed question is simply, no. As much as we humans like to separate ourselves from all other animals and from nature in general, we are a huge part of the natural world. And, as part of the natural world, many animals have evolved to coexist with us and our cosmopolitan ways, spiders included. Though there surely can be species that roam into homes randomly from time to time, there are a number of spiders that live in/on man-made structures for their entire lives. For example, the Common House Spider (Parasteatoda tepidariorum) prefers to build webs on or in buildings (if you live in the U.S., you have probably seen them in barns, sheds, attics, etc.). Moving these spiders and other house spiders to bushes or trees outside would not help them survive, and would be an unnatural habitat for many spiders found in the home.
Answering the second part of the posed question is a bit simpler: we don’t like seeing spiders in our homes because we think that they are pests. However, spiders are more like pest control, than pests, themselves. Many house spiders eat insects like mosquitoes, fruit flies, ants, and cockroaches – essentially, all the bugs that we really don’t want in our homes.
So, if you can, try to accept the spiders that you see hanging out in your house, because they’re more likely helping you than harming. However, if you really can’t stand the sight of them, and you absolutely have to move them somewhere else, try to move them into a shed, or attic/closet you don’t access much, instead of outside.