The type of data being discussed here (factual data about people) cannot be copyrighted - i.e. the fact John Doe is a Software Engineer for ACME Inc is not copyrightable.

A better example I think is walking into a store and writing down what they price everything as, then selling aggregate pricing data to people. I can't see any reason that would be illegal.

Would likely be illegal if you continued to do after the store asked you to leave...

Compilations can sometimes be protected.

Well its a Database Right, which is a property right rather than copyright.

https://en.wikipedia.org/wiki/Sui_generis_database_right

As with all rights, it varies with jurisdiction.