An awful lot of people work in a corporate desktop environment where the machines are bolted down. They don't go home with you. You don't have admin privileges, you can't install software, and there's probably corporate spyware installed.
Customer service. Tech support. Inbound sales. Outbound sales.
The company doesn't trust you. If you take a machine home, you're probably going to lose it or break it or sell it, so that's a hard no.