Examples of necessary things. If the wisdom teeth are coming in straight, they can stay (although most dentists will remove them anyway), but they usually come in at an angle, and need to come out so that they don't cause problems. I agree with you that dentists overdo this one, but for many people it is actually necessary.

In the US, we have 3 kinds of schools:

* Public/state schools: The school is run by a state government. Some of these have good quality, but some are not good. All of them give a huge discount to students from the local state.

* Private for-profit: These usually all suck, and are scams. ITT tech, University of Phoenix, and others are in this boat. These make their money by providing an education for less money than they charge in tuition.

* Private non-profit: The school is organized and run as a non-profit institution, but is not connected to the government. Harvard, MIT, Stanford, and most other top colleges are private non-profits. Outside the US, I think Oxford and Cambridge are also like this. Private non-profit trade schools also exist, and they are usually the best ones. An example I can think of is the North Bennet Street School (again in Boston, MA). The high-end schools in this category tend to get more of their money from donations and endowments than from tuition.