Los Altos's anti-gypsy ordinance

Article IV, Section 2 of the Constitution of the United States guarantees citizens certain "privileges and immunities." The Supreme Court has interpreted this to mean that neither states, counties nor cities can discriminate against non-residents' economic activities without a "substantial reason" for doing so.

All of this leads to the following question:

What could possibly be the substantial reason Los Altos has for limiting fortune-telling and palm-reading permits to residents of the county? (See Title 4, chapter 16). Was there a huge problem with gypsies blowing into town and ... doing what exactly?

The offending part of the law reads:

No person shall practice the business of palmistry, fortune-telling, astrology, prediction of the future, or any similar practice for a fee or any other item of value without first having obtained a permit from the city manager.

...

Any person holding a permit pursuant to this chapter shall be a citizen of the United States, of good character, over the age of twenty-one (21) year, a resident for one year last past of the county, and have a city address wherein operations will alone be lawful.

Another part of the law excludes would-be fortunetellers who have previously been convicted of trickery or deceit.

If any non-residents out there are interested in applying for such a permit and bringing a federal court challenge when the city refuses, I am your lawyer.