Re: [ANNOUNCE] CoinWorker.com beta - earn bitcoin in minutes via tasks in browser
I think he said earlier that the jobs are provided by different people and the company he gets them all from just puts them together. So the different people are 'competing' for you to do their jobs by providing more pay and making them easier than others. So by not doing that job, you're convincing them that they need to pay more to get it done. 
Indeed. I think I've seen tasks come back with changed payouts. I've definitely seen the UI improve to make answering quicker and easier: the interface for rating ecommerce search results used to require a lot of manual scrolling and had no keyboard shortcuts.
The tasks on offer seem a bit thin now but definitely in the long run, the projects injecting tasks are competing against each other for contributor attention, and making their tasks pay more or have smoother interfaces and clearer standards are some ways they compete.
{Warge