One angle is that stereotypes form because of something happening so frequently that people notice it (and I'm not talking about the racist stereotypes that are typically untrue and used negatively, so much as the ones provided above that may be argued to be observational stereotypes). Some statistical analysis would be needed to see if there were indeed more people in those occupations that meet the stereotype than people from other segments of the population and, unfortunately, I'm not aware of any offhand. Bear in mind that the 1st two examples you give are low paying jobs. The people that fill those jobs tend to be newer immigrants and the background of the person fitting the stereotype will vary over time and by location (particularly the taxi drivers) depending on where the recent wave of immigration is coming from. 10 or 20 years ago, the stereotype of a taxi driver would not have been someone from Somalia. Also, having lived in the UK, the stereotypes differ there, because there is a different pattern of migration to the UK than there is to the US. For the 2nd two examples, markets are a big part of Middle Eastern culture and food is a big part if Far Eastern culture - ones that fit into market openings in the US. They might just be using their experience and capital advantageously. Then again, perhaps you don't notice all the instances that don't meet the stereotype but, because someone has created the stereotype, you are aware of it when you meet someone that does fit the stereotype. Therefore, the concept of a stereotype is, by it's nature, self-fulfilling. It's like our perception of coincidence. When a coincidence happens you think, "what were the chances of that happening." However, that isn't correct thinking because you are not aware of the whole statistical population in making that statement. Say you bump into someone you knew as a kid and haven't seen for years. That seems like coincidence but you're not counting all the times you never met someone you knew as a kid and haven't seen for years (some of those times possibly even including times when you were right next to such a person and just weren't aware). BTW - I don't see a predominance of people owning restaurants being Asian outside of Asian restaurants - which admittedly are very popular - so I don't know if that stereotype holds true. Sorry for the ramble (I tried to keep it concise) but that's my personal take on the matter. Oh - and I'm Scottish. We're stereotypically tight with money. Someone once asked me if that was true. I offered to tell him if he paid me $5.