Because your phone is not working correctly. You can complain, and cry about it all you want, but that's not going to get it fixed. There is not going to be a supplementary patch from Verizion or Samsung to fix this. I suggested these troubleshooting steps to Mizzely so that she could try them and see if they would work. Some on the site have done that and have sucess and other have not. I try to help those with the knowledge I have, if you don't like what I suggest, just ignore it and live with what you have.
My wife and I have the same problem. My wifi works without a problem at home and she has issues throughout most of the house. Did any of the solutions work for you or did verizon have a solution? Very odd that the exact same model phone can behave so differently.