My buddy just got a job at a high-end cocktail bar as a bartender. Part of the interview process was asking him to mix a drink.

Gordon Ramsay has talked about how he'll interview chefs by asking them to make scrambled eggs.

Actors, even famous ones, generally have to 'read' for roles in order to land them.

Musicians interview for seats in symphonies by playing music.

MBAs have to do case studies to land jobs at high end consulting firms.

Hell I applied to Taco Bell as a kid and they made me take a short math test to prove I knew how to make change.

I could give similar examples for dozens of other jobs.

The cases where you don't need to demonstrate some skill in order to get the job generally fall into a few categories:

- There's some outside certifying body like the Bar, CPA, PE, various tradesmen unions, or all the licenses like a CDL.

- The jobs are undifferentiated so the workers are fungible (no special skills required).

- Job skill is immediately apparent (less than two weeks to know for certain if someone can do the job or not).

- The cost of a bad hire is low so you're willing to eat the cost and just cut the workers how don't work out.