Surveys can be complicated, but that doesn't mean it's impossible to complete them.
Take email submit offer for example. The advertiser has to make money too.
They'll get your email and redirect you to survey, even when you complete that survey, they'll redirect you to another one, and another as long as you're willing to do them, they'll keep sending you there.
Even if you quit after one or two completed surveys, that doesn't mean the publisher won't get paid for it. They just send you to more and more so they can make more money...