The economic forces at work are supply & demand, and a process referred to as voting with your feet. Every time someone or some society gives more to a homeless

The economic forces at work are supply & demand, and a process referred to as voting with your feet. Every time someone or some society gives more to a homeless person they increase demand - in a sad twist of intentions and results they increase the negative effect they're trying to alleviate. Homeless people are also able to move more easily as they have so few possessions and a lower cost of moving. If San Jose provides relatively better conditions for homeless people than Las Vegas, then San Jose ends up with a correspondingly higher homeless population.