What are your thoughts about 'homework' during the hiring process?

IMO, if I'm to do any work (including solving problems that are of no use to the company) then I need to be compensated.

In sales the idea is to give the 'what' but sell the 'how'. Why is it accepted that giving away the how to potentially get value in return is standard in engineering?

I'm baffled by the disconnect between the competitive battlefield of the talent environment and the entitlement to time in the hiring process.

What are your thoughts?