1. Speaking in the broadest sense, most jobs are designed around you having to interact with one or more persons, sometimes in a stressful and pressured fashion, every day. Some of it even involves you trying to convince people to buy your product. I'm sure most people on the spectrum would rather not be bothered with that.
2. Some, if not all, cities have an inordinate amount of noise - motorcycles, car horns, traffic, etc. Definitely not conducive to mental health.
3. I don't know what the percentage is, but a lot of folks on the spectrum don't like crowds, so shopping in the mall or a supermarket is definitely a no-no.
4. Again, I don't know the percentage, but some folks on the spectrum could care less about current fashions and often ignore places like Nordstrom's, American Apparel, Macy's, etc.
5. Parks, convention centers, movie theaters, etc can be nightmares for spectrumites because of the crowds, noise, amount of people and protocols often involved with those venues.