If your goal is to have people click on your ads, what other denominator is there than the click-through percentage? Google is a middleman for advertising, it'

If your goal is to have people click on your ads, what other denominator is there than the click-through percentage? Google is a middleman for advertising, it's not for them to judge whether their viewers are worthy of clicking on their ads. And do you really think there's a socio-economic divide along the lines of blue vs. yellow text ads? Because that's pretty ridiculous.