anti-weed controlled environment

So let's say an isolated lot of land is developed for residential use. The ground is completely weed-free, just theoretically speaking. No weeds whatsoever. Houses are built. Sod is laid. People move in. Lawns are mowed. People go about their lives. Now, will weeds ever find their way into this community? Is is possible for the lawns in this community to live without weeds? A man can dream.

Someday I'll have a lawn and it will be pristine. Everyone will be able to play croquet without a single hazzard, even a dandelion.

I will never have children though. I think if you have kids you should let the weeds grow. How will they ever learn to pluck a dandelion from the lawn, plant their thumb under the flower, pop it off and exclaim "Mamma had a baby and its head popped off!"? There is no telling what not having that experience could create later in life.

If you build it.. the weeds will come.
I think unless the area is closed off with a giant bubble dome, and people are thoroughly decontaminated before entering, that it's almost impossible to keep the weeds out. Wind and humans are the best spreaders of weeds around.. Hell, we managed to spread dandelions from Europe to North America.

I was trying to find figures for how far wind can spread a dandelion seed.. didn't find it, I'm assuming it could be REALLY far though.
I thought that if you got most of the root, that the darn things would die. Turns out that they spread by their roots too, so if you try to pull out a root and fracture it into 2 pieces (that remain in the ground).. *poof* now you've got two dandelion plants.

Sorry Moose, but weeds are almost as certain as death and taxes. They will find their way to any patch of dirt by way of wind, animals, insects, or humans.

And Tom, don't worry about letting the weeds grow just to avoid depriving children of the joy of dandelions plucking. Even if you take an active role in preventing weeds from entering your lawn, you will still get occasional dandelion.

I fertilize and or use weed control products on my lawn 4-6 times per year and I still get them periodically. I have FAR less than my neighbors, but still...

Weeds can be carried by birds building their nest.

You'd have to keep out every living thing larger than a dandilion seed, including yourself, which would defeat the purpose.

A variety of weeds and plants beats the heck out of a boring old golf course monoculture anyway, for all the reasons others have mentioned.