The low man on the totem pole gets treated the worst? No matter what the situation calls for, superiority always rears it's ugly head.
Restaurants. You can't have a restaurant without servers or dishwashers yet many people frown upon these jobs like they really are the bottom of the barrel. Grocery stores are another great example. Granted, many cashiers could use a major attitude adjustment but without cashiers a grocery store couldn't operate even when you think of the alternatives. Self checkouts are great but not everyone feels they should have to scan nor bag their own groceries. Sadly, may people don't have the common sense to operate them either. Same goes for the kid who collects the carts. Heaven forbid people should walk ten feet out of their way to return the cart but yet the cart collector is just a dumb kid. See where I'm going with this...
All of these scenarios can be played in just about every field.
Utility companies-meter readers
I just don't think people realize how significant each of these jobs are. Ironically in this economy though, many people who once looked down their nose at this jobs now wish they had one.