When someone sees glowing reviews and completed jobs, you become the "easy button" and they will pay more to decrease their risk. When they see 10 completed jobs with 5 star reviews, all mentioning the exact type of work they need, they can be pretty sure the 11th will be successful. It's possible to charge $125 or more an hour on UpWork and have to keep your settings updated so that you are not spammed with invites.