But in pricey California, with its soaring housing costs, the homeless, working poor and even middle-class workers are sharing the Wal-Mart lots with footloose retirees and vacationing families.
As worries about long-term encampments mount, more and more cities are forcing Wal-Mart to limit or prohibit overnight stays.
Information technology specialist James Hirtzel, 32, parks his compact camper in a far corner of the Milpitas Wal-Mart lot several times a week. He used to sleep outside the Mountain View store but was recently asked to stop parking there.
"It was only five minutes from my job, but one morning I woke up and found a nice, congenial note on my windshield saying, 'Please don't park overnight,' " Hirtzel said. "So I left and started coming here."
Hirtzel isn't homeless. He and his wife own a house in Sacramento, and their combined incomes add up to six figures. But the couple have three children, and even with two salaries, they say they can't afford to live closer to the Mountain View pharmaceutical firm where Hirtzel works.
So he outfitted a used camper with satellite TV and a Playstation 2, and spends most weeknights away from his family.
"It's not ideal," he said. "But like a lot of people here, I'm trying to make ends meet."
That's Wal-Mart for you, transforming the working poor into a new indentured class.