This reminds me of how unions used to certify that their members were competent. Specifically, the Carpenters' Union in my area administers tests for different

This reminds me of how unions used to certify that their members were competent. Specifically, the Carpenters' Union in my area administers tests for different levels of skill, and rates union carpenters based on the results of these tests. To be rated a Journeyman, for instance, the test requires you to demonstrate competence at a variety of carpentry techniques that would be required in framing a house or concrete form, for instance. Then you pay your dues and can be added to the list of union members without a job. Then when you hire someone whose union represents that they are a Journeyman, you can be confident that they're competent.