You have no right to drown in my pool!

In an earlier post, I likened American freedom to an attractive nuisance, and sarcastically discussed ways of making it less attractive to illegal immigrants.
Mickey Kaus thinks the country is an attractive nuisance, but he calls for the more traditional remedy of a fence:

The logic of seems inescapable. The U.S., in this sense, is an attractive nuisance like a swimming pool. If you want to keep neighborhood children from using the pool, and possibly drowning, you don’t partially fence it in. You completely fence it in. … Full funding for full fencing!

Via Glenn Reynolds, who adds that “Mexican immigrants are adults, though, not children.”
My previous sarcasm aside, I think it’s better to build a fence than get rid of the pool.
The only problem with the swimming pool analogy is that some people — including adult Americans — can’t seem to handle their own freedom, but they are allowed to swim anyway.
Should American adults be protected from drowning?
In their own pool?
MORE: Maggie’s Farm, after noting the origin of the phrase “good fences make good neighbors,” also makes the attractive nuisance analogy:

And I also wonder about this: We must have fences around pools, but not around rivers and ponds and lakes – or the ocean. And no fences to protect our national borders. Which is more important? I don’t mind being Frost’s practical but un-soulful neighbor: I will gladly provide both my pool fence, and my national border fence: The law may be an ass, but it’s the law.

Interestingly, in Mexico people not only build fences around their property, they build walls. And why not?
Is there something wrong with privacy?