Where do people get the public mail records from?

Im curious as to where all these list people are getting mail leads from. If I wanted to know what the addresses and names of the people on my block are wouldn't it be listed in public record somewhere. Why should i have to pay 7-9c a lead to get this info. Isnt there a database somewhere that I can log into and query these records?

any thoughts?

Yes there are public records but it takes time to gather the required information.
Also depending on the amount of research you do the end result will be pretty untargeted.
Eg x no of people in x location
Buying a list saves time and you can specify your requirements to make the list targeted.
Eg x no of people who drive in x location, x no of people who have young children in x location, x no of people with pets in x location.

Everyone has their own method. As for example, you can run a call center for doing this. Cold call phone numbers for lead. Tell them that this is a phone address verification call and offer them something for submitting the information ( apply your twist here ).

Phone number lists are cheap for countries like US, canada, Ireland and so on. This method works and I have worked in such process before. Alternatively, you can scrape phone numbers online for crud lead.