I took Amtrak on a weekly basis for about 3 years and I was never searched nor did I ever see anyone searched.
I have driven up and down the west coast from Canada down to Mexico and have never been searched.
Yes, I know my anecdotal experience doesn't mean anything but the picture you paint makes it seem like you can't go anywhere without being searched, realistically the only form of travel where you will be searched is when you fly. Anyways, that's not my point. My point is that we as a society have agreed to give up certain liberties in exchange for safety. For example, we don't allow people to drive without a license. We don't allow you to carry invasive species from one state to another. We don't allow random people to walk through your property. These laws exist for a reason and they weren't created to solely impede on your rights. Sure, we may disagree on where we draw the line but it doesn't help the discussion if you act like we still live in the 1700s where you can hop on your horse and not worry about being searched when you cross the border.
Usually 4 cops and a little table setup with some device they enter tiny paper samples in. NYPD cops. They profile as some people are not stopped.
EDIT: Okay I found the picture for you although this is not station I refer to:
http://cdn.newsday.com/polopoly_fs/1.10508690.1433457042!/ht...
You are also free to travel without body searches, just not on a subway, at least in NYC where they often setup mandatory checkpoints before you enter the platform.
Also more and more COBRA teams are swooping through Amtrack and yes they do search your property.
You are also free to travel without body searches, by a car; unless you are in a border zone of 150 miles, which currently covers the entire state of Forida, for example.
Once you get through all means of transportation, you can always walk without body searches. The problem is you won't get further than your local cigarette store, as the most highways are closed to pedestrians traffic and there is practically no other way to travel through cities/states, unless you okay with transpassing someones property along the line.