It works essentially the same way as the phone apps do above. If you don’t care to let Google know what you do on a daily basis, you can make money from home by letting them monitor your Internet usage. They use the information they gather to help them market/increase the functionality of their advertising programs when targeting users that are similar to you.
You cannot possibly know if you’re being paid what you’re worth if you don’t know what others in your field are making. Sure, you can do some blind research on websites like Glassdoor and Payscale, but nothing is going to light a fire under you like learning that Ned who sits in the cubicle right next to you and works half as hard as you is making $5,000 more than you.
Essentially the same thing happened in China with clocks: one emperor's decision abolished clocks over China. China was also on the verge of building powerful water-powered machinery before the Industrial Revolution in Britain, but the emperor said "Stop," and so that was the end of the water-powered machinery in China. In contrast, in Europe there were princes who said no to electric lighting, or to printing, or to guns. And, yes, in certain principalities for a while printing was suppressed. But because Europe in the Renaissance was divided among 2,000 principalities, it was never the case that there was one idiot in command of all Europe who could abolish a whole technology. Inventors had lots of chances, there was always competition between different states, and when one state tried something out that proved valuable, the other states saw the opportunity and adopted it. So the real question is, why was China chronically unified, and why was Europe chronically disunified? Why is Europe disunified to this day?