Performance Metrics: Many companies view this as overhead. It's sort of a pain in the ass, so if I have to do it because my employee is working on the side, then he needs to carry the burden compiling the metrics. He could stay on-site an extra half hour per day and generate a report on what he did, or I could generate the metrics, and just pay him a little less for this inconvenience.
If he's your employee, you really should have a feel for how long it takes him to get something done. You should also know what sort of quality to expect from him.
If you can't determine those things, then one of you is not doing your job already.
