Waiting for Walter to get to the facility, Jesse decides to goof off. When employees aren’t being monitored, there may be an incentive for those employees to shirk (goof off) while still being paid. If firms pay efficiency wages, that may incentivize some workers to avoid shirking, but it’s not always guaranteed.
When employees have the ability to shirk or steal, firms may invest in monitoring devices to ensure against theft. In the lab, Walter supervises Jesse, but their employer monitors both Walter and Jesse as they work. Hypothetically the guard may be paid a handsome salary to disincentivize him from cheating his employer.