Why would Amazon pass that information to turkers?

"Find city, county, state in this list and post in the three boxes "City" "County" "State" in the web form." is literally all the information required for this task. All of the rest can be handled by Amazon's staff, or more likely automated processes. The turker need not know for whom they do the work, or why. They could be processing marketing communications, or census returns, or credit card applications, or literally anything else where an address may be used.