Nowadays more and more companies hire people to advertise their products by standing on corners and holding a sign for oncoming traffic. These hired people spend five to seven days a week in the streets. They are waving a store sign and dancing to music, pumped into their ears by the walkman/MP3 player on their belt. This phenomenon happens not only in the USA, but all around the world, and is called the human billboards advertising.
The human billboards (trivision billboards) advertising existed long ago. One of the first large processions of trumpet-parping placard-carriers took place in London in 1834 (they showed the message, 'All the Alamanacs are given away with the Bells Weekly Messenger'). This is despite the fact that the A-frame sign was invented years ago. Today it can be purchased for about one hundred dollars and businesses could use them for weeks, months and even years. It depends on the wear and tear the signs get or the message a business wants to convey. At the same time, if you include a wage, a workers' compensation insurance, Social Security taxes, etc., you will see that a minimum wage at which a human has to be employed is more than one hundred dollars a day.
Here is a question: Why would many businesses do this? Many people think that "the main reason for the employment of human billboards is that A-frame signs are illegal in most cities in the bay area." A great number of different signs all over the streets can cause some tremendous eyesore to pedestrians and drivers. In many cities, they try to limit these inconveniences. Besides, using A-frame sign bans for advertising can cause some safety problems - people might walk by one of these signs and trip over them. As with many other things, here are also many restrictions implemented in advertising laws by the politicians (political advertisements, unfortunately, are everywhere and completely legal).
Real estate sales people also belong to that special group, exempted from these regulations. Open house signs can be put up by them for the weekend. Every person that is selling (or will want to sell) a house is a city resident. Thus, the restriction of sales advertisement would be impossible to impose on the citizenry. As a rule, business owners are not city residents. That is the reason why they cannot stop strict and useless regulations that usually go on to stop other attention getters like large signs, balloons, etc. from being enacted.
There are no cities, however, that can regulate free speech. That one is in the Constitution of many countries of the world and is non-negotiable for city and local governments. Hence, it is perhaps the only way out for businesses to exploit this weakness in the city's ability to regulate by paying a person to hold up a sign on the street corner.
This job of a human billboards advertiser is very hard and unpleasant and sometimes even dangerous. That is how one of former human billboards depicts the job: "Hanging around all day looking like a chump with a great big billboard above your head has to be one of the worst ways to earn some money. I've certainly had some hands-on experience of the job - for the sum of £5 an hour, I had to hang around tube station exits at 7am dressed as a gorilla, handing out leaflets for a sandwich bar. I felt awful and grumpy commuters on their way to the office weren't impressed either - in fact, several went out of their way to tell me so!"