[passivate]

> Why would I care which plumber paid Google the most money? I just want to find plumbers.

Yes, exactly! Also, To your second point, its in Google's interests that customers have no other way except paid ads to look you up. IMHO, Google has become a company that wants to install toll booths on the internet.

[bigger_cheese]

Businesses have to pay to advertise in phone directory already so I don't think this is much different and as other commenter suggested presence of a paid ad suggests service provider may be more reputable.

[passivate]

Sure, but then the framing is "we're just as bad as these other guys".